The major issue of the aeronautical field is to deal with a constant weight reduction, while keeping the same or increasing the safety. Impact of accidental fragments on aircraft bodies have to be considered for the design of aircraft. The use of numerical simulation to predict the behavior of structures has seen an exponential expansion since the last years. It has become an essential tool to reduce developing time and cost, especially, material parameters are very important for high accuracy of computer simulations. Fracture strain is important to simulate fracture behavior and locus. It is now established that the stress triaxiality clearly affects fracture strain of ductile materials, but details and important factors were still unknown. The effects of stress triaxiality on fracture strain of aluminum alloys have been studied. However, the amount of data related to aluminum alloys is still low. The effects of stress triaxiality, Lode angle parameter and strain rate are not fully clarified. Hence, effects of stress triaxiality on fracture strain of aluminum alloy 2024-T3 were measured using plate-type specimens. Fracture strain was accurately measured using 2D-digital image correlation (DIC) method. Numerical simulations under the same conditions were carried out using finite element code LS-DYNA. Fracture strain decreases as stress triaxiality increases. Numerical simulations were good agreement with the experimental results.

Understanding of rubber friction on a rough surface is one of the fundamental issues to develop the integrated engineering design method for tires and roads. In this study, we measure the power spectral density of surface roughness, called surface roughness power spectrum, for the three types of abrasive specimens and identify the surface parameters featuring the self-affine fractal surfaces. Using the measured surface specimens, we demonstrate the friction tests for tire rubber to control the surface temperature and sliding speed. To compare among the three master curves obtained from the measured friction coefficients, we investigate the relationship between the speed dependency and the power spectra. Based on the experiment data of the friction and abrasion tests, we discuss how the hysteresis effect of the rubber and the other friction factors contribute to the friction force.

In recent years, studies on frictional sliding behavior at the nano-scale and meso-scale have been widely conducted. However, there are few studies that consider for multi-scale. Therefore, in this study, we propose the multi-scale analysis method of rate- and state-dependent friction. As a macro-model, the rate- and state-dependent friction model based on elastoplastic theory is adopted, while he multi-point contact model consisting of a large number of spring-mass systems is adopted as a meso-scale model. We show that the microscopic elementary process in the finite element analysis introducing the macro model can be examine the meso-scale behavior of rough surfaces.

In this study, we proposed a simple prediction method of adhesion friction between rough rubber surface and smooth hard surface by combining Persson’s contact theory, the basic friction test and finite element method. In addition, the validity of the proposed method was verified by comparison with actual test results. As a result, the load dependence of friction coefficient can be rationally expressed by the proposed method, and it is found that the order of the friction coefficient is the same as the test result. Furthermore, the friction test of the grooved rubber was reproduced by the finite element analysis as prediction of the frictional force in an arbitrary shape, and the prediction accuracy of the proposed method was confirmed.

Measurement of road surface friction coefficient is significant to improve advanced driver-assistance systems (ADAS). Generally, ADAS uses information obtained from wheel speed sensors, acceleration sensors, etc. However, it is difficult to measure accurately road surface friction coefficients with these sensors. Therefore, various studies that focuses on a tire that is only portion to contact with a road surface in a car have been conducted to develop an intelligent tire capable of measuring road surface friction coefficients. However, an intelligent tire capable of measuring road surface friction coefficients have not been put to practical use due to the difficulty of stable measurement of deformation of a tire and the difficulty in measuring road surface friction coefficients from the deformation of a tire. This study proposes a method to measure road surface friction coefficients from strains induced on the side of a tire, which is easily detected. We clarify the relationship between strains on the side face of the tire and loads acting on the tire at grounding surface using an experimental apparatus capable of simulating complete slip running with three axial loads applied to the tire and propose a simple method of measuring road surface friction coefficient from the measured strains.

In this study, we derive a closed-form solution for linear elastic properties of swollen elastomers. To this end, linear perturbation analysis is applied to the Flory-Rehner theory. Instead of the Neo-Hookean solid model in the theory, the strain energy function is assumed to consist of three invariants to obtain the most general expression.

The cylindrical rubber is axially reinforced by the fiber and closed by the rigid ends. When the inner pressure is applied to this fiber reinforced rubber cylinder, the diameter expands and the length shrinks. Such the cylinder can be used as the soft actuator, that is, the artificial muscle.This artificial muscle has high contractive force and amounts compared to McKibben-type artificial muscle which is used widely. However, durability of the artificial muscle is not enough for practical use. In this paper, we analyzed the rubber cylinder theoretically. Firstly, the differential equation, which is satisfied the cylinder's profile, is derived. Secondly, the solution is obtained as the closed form, when the rubber is soft enough compared to the fiber. Finally, it is found that the profile of the rubber cylinder is given by the incomplete elliptic integral, when the inner pressure is large enough.

Rubber is widely utilized as industrial material using its unique material properties. Since the properties are controlled by recipe, mixing and curing of rubber, research and development are active based on polymer materials view point. However, from materials and mechanics view point, fundamental material properties should be measured for each rubber. This leads difficulty to shear investigated results between researchers. In order to promote materials and mechanics research for rubber, research society activity started to propose standard specimen for investigating and shearing mechanical behavior. After surveying standard of rubber materials, a standard Styrene-butadiene rubber specimen was proposed including recipe and production method. The first specimen is made and carried out uniaxial tensile test.

Nondestructive inspection methods using infrared thermography for detecting delamination of surface finishing material such as tiles or mortal on concrete structures have been employed for a long time due to their advantages of effectiveness being able to measure a wide area at once. However in the case of using infrared thermography having a sensitivity in 8-14μm spectrum band used in ordinary building inspection, there is a problem that infrared images are influenced by the reflection of surrounding infrared emitting sources such as solar radiation or high temperature heat sources. In this study, infrared ray in 5-8μm spectrum band is utilized its low reflectivity on shiny white tile surface and high spectrum absorbance of atmosphere for avoiding the reflection. Infrared thermography having a sensitivity in 5-8μm spectrum band is developed based on microbolometer infrared camera to make it possible to reduce the reflection on building surface. We measure the temperature distribution on the surface of the building using the infrared cameras having sensitivity in 5-8μm and 8-14μm spectrum bands. From experimental results, we found that 5-8μm spectrum band infrared camera has the ability of reducing the influence of solar reflection as well as the defect detectability.

Heavy anticorrosion paint is applied on the surface of steel bridges for protecting corrosion. The heavy anticorrosion coating is composed of multiple paint layers such as zinc rich paint undercoating for electric corrosion protection, epoxy resin middle coat paint for protecting the zinc rich paint, and weather proof fluorine resin top coat. In the maintenance program of steel bridge anticorrosion coating, it is important to decide the timing of repainting repair, and in general the timing is set when the weather proof fluorine resin top coat is lost. However it is difficult to detect the loss of top coat by visual testing. Therefore it is beneficial for the preventive maintenance to determine the wear of top coat quantitatively before the top coat is completely lost. In this study, experiments were conducted with the aim of quantitative estimation of the degree of abrasion of the top coat thickness. It was found that it is possible to estimate the topcoat thickness based on the infrared luminance value.

Actual structures are exposed to arbitrary average stress, and evaluation using a modified Goodman diagram is widely performed. However, it has been reported that there is a material to which these diagrams cannot be applied, and in some cases the fatigue limit drops significantly. Therefore, the authors developed a method to quickly estimate fatigue limit using temperature change and plastic strain energy measured by IR thermography, and examined its effectiveness.

On the infrared thermography image, an apparent temperature change caused by the relative displacement between moving object and infrared camera is obtained. This paper shows the motion compensation system with the optical-infrared synchronous measurement. Displacement information of the specimen is calculated from the series of optical image using the digital image correlation method. The displacement information on the optical image is reflected to the infrared image by homography. For obtaining the displacement information by digital image correlation method, random pattern on the surface of measured object is required. In this study, white random pattern was drowned by the sputtering painting method. The motion compensation system was applied to the thermoelastic stress analysis for the specimen having a circular hole. It was confirmed that the apparent temperature change and edge effect can be removed by using developed motion compensation system.

In order to maintain the safety of infrastructures such as steel bridges, it is important to detect fatigue cracks by nondestructive evaluation, to evaluate crack propagation rate, and to verify the effectiveness of crack repair.One of the effective non-destructive evaluation methods for these purposes is thermoelastic stress measurement by infrared thermography.In this method, stress distribution is measured based on the temperature fluctuation due to the thermoelastic effect. It enables us to conduct remote nondestructive and noncontact measurement of stress distribution.In this study, a plate bending fatigue test was carried out using specimens simulating steel members with fatigue cracks in actual bridges. The relationship between crack propagation rate and stress intensity factor range were obtained from measured stress data. It is found that obtained relation agrees well with the Paris law. Based on the experimental result, the reduction of crack propagation rate by the repair works in the actual bridge is estimated.

When ultrasonic testing is performed, the artifact appears in ultrasonic flaw detection image since longitudinal wave and transverse wave occur by mode conversion and receiving wave cannot be discriminated between these waves. The goal of this study is to discriminate between these waves in order to decrease this artifact. In this research, localizing method of AE source and three-axis sensors as receiver are introduced. The point where incident wave finally reflects before arriving at receiver is localized by utilizing localizing method of AE source. The propagation direction of received wave is estimated by using the localized point, and the vibration direction is measured by three-axis sensor. The angle between the propagation direction and the vibration direction is calculated. As a result, two angles are calculated in the case of assuming that received wave is longitudinal wave and the case that received wave is assumed to transverse wave. By investigating which of the angles value are closer to theoretical angle value, received wave is discriminated between longitudinal wave and transverse wave. The effectiveness of this discrimination method is verified by using ultrasonic propagation simulation.

CFRP with continuous curved fibers were manufactured by using 3D-printer and ultrasonic which propagates on the CFRP was investigated. In order to visualize the propagation behavior of ultrasonic, we used Laser Ultrasonic Visualizing Inspector (LUVI). By using this equipment, we visualized the propagation on a CFRP plate which have concentrically curved fibers. As the result of the experiment, it was found that ultrasonic propagates along curved fibers. It was noted that this phenomenon affect the source localization of AE testing when conducting CFRP with curved fibers.

The reflection and transmission of Lamb waves at an adhesively bonded lap joint of plates are numerically analyzed by hybrid finite element method (HFEM). The adhesive joint is modeled as a linear spring-type interface characterized by normal and tangential stiffnesses. The numerical analysis is carried out for a low frequency range in which only the lowest-order symmetric (S0) and antisymmetric (A0) modes can propagate in adherends. For the A0 mode incidence, not only the reflection and transmission of the A0 mode occurs at the joint but also the S0 mode is generated as reflected and transmitted waves due to mode conversion. The numerical results show that the reflection and transmission coefficients of both modes exhibit local maxima/minima at different frequencies. This behavior results from multiple reflection between the edges of the overlap region. The peak frequencies of the A0 mode reflection/transmission coefficients depend only on the tangential stiffness of the interface, not on the normal stiffness. The theoretical prediction shows that in the overlap region, i.e., a bonded double-layer plate, two types of guided wave modes, symmetric and antisymmetric modes, can propagate. Since the dispersion properties of the symmetric and antisymmetric modes depend only on the normal and tangential stiffnesses, respectively, the antisymmetric modes are found to play an important role in the multiple reflection leading to the peak behavior of the A0 mode reflection and transmission coefficients.

The higher harmonic generation characteristics at contacting surfaces subjected to an obliquely incident ultrasonic wave is studied experimentally. To this purpose, a 10-cycle, 1-MHz longitudinal burst wave is sent to the contacting interface of aluminum blocks with the incident angle 45°. The amplitudes of the fundamental and the second-harmonic components are evaluated quantitatively by calibrating the voltage amplitudes obtained by the piezoelectric transducer against a laser-Doppler vibrometer. The results are compared to those for the normal incidence. The influence of the contact pressure and the surface roughness on the harmonic generation behavior is examined.

In the impact acoustic method the excitation force has to contain the frequency of the defects which should be detected. The frequency of a steel ball impact is able to be obtained from the change of the contact force with respect to the time. However the mechanism of the excitation due to water jet is different from the elastic ball, which is generated from the momentum conversion into impulse. In this paper the excitation force of water jet impact was measured by a pressure sensor and compared with the simulation results which was obtained from the water droplet intervals and the size. The frequency range of water droplets discharged from a 5 mm nozzle was up to 2.0 kHz.

Moment of inertia is an important factor for rating a performance of mechanical products with rotational motion. Inertia moment can be designed, but the wooden products of it may vary due to the individual difference between timbers. Moreover, mass moment of inertia may change over time due to factors such as spoilage, corrosion, and drying. Nondestructive evaluations of mass distribution are important to improve the inertia moment of the actual product. The author have proposed a non-destructive method to estimate mass distribution and internal shape in solids. In this method, mass distribution is estimated by an inverse analysis of inertia moments which are measured at several rotational axes. It is possible to detect internal voids using this method because estimated masses become zero there. The material densities can be also calculated from the estimated masses and the shape. In the previous study, numerical simulations for buttcylindrical rods were carried out to prove the effectiveness of this method. Relatively high estimation accuracy of this method was obtained by an inverse analysis when there are two unknown parameters. In this study, I tried to apply new approaches for the problem including relatively large number of unknowns, however it was difficult to improve the estimation accuracy.

In accordance with the aging of steel structures, fatigue of metals becomes a serious problem and countermeasures are required, because fatigue crack may lead the structure to catastrophic breakdown. “Crack growth arrester or retardation system”, developed as a versatile and high performance construction method against fatigue crack growth, by using arrester to close fatigue crack and reduce stress concentration at the fatigue crack tip. Arrester was applied to CT (Compact Tension) specimen and steel bridge deck specimen, in order to verify performance of the system and to investigate the range of application. According to the result of fatigue test using CT specimen, fatigue crack growth rate of the specimen with arrester was 2~10 times lower than that of specimen without arrester, and the threshold value of apparent stress intensity factor range was 10~20MPa√m higher than that of specimen without arrester. Specimen with stop hole required high load level to relapse fatigue crack; however, after relapse of fatigue crack, fatigue crack growth rate of the specimen with stop hole was same as that of specimen without arrester. Also, the arrester was applied to the fatigue crack which was introduced in steel bridge deck specimen. Without arrester, fatigue crack extended in accordance with the increase of loading cycles, on the other hand, fatigue crack growth stopped after construction of the arrester.

The purpose of this study is to develop the creep life prediction method based on the extreme value analysis of maximum surface lengths of multiple-site small surface cracks found in high-temperature creep of an austenitic stainless steel SUS316L. Creep interruption tests of the steel were conducted at 873K and 948K in air in order to measure the positions and the surface lengths of multiple-site cracks by using scanning laser microscope. The optimum area for the determination of the density and the surface length distributions of the cracks observed. The area is the smallest area that can draw the inference for the statistical distributions of all the cracks found on the surfaces of the specimens. The maximum surface crack length distributions were inferred and the return periods were obtained for the prediction of creep lives. The result showed that the predicted creep lives agreed well with the experimental creep lives for all the tests performed.

Small fatigue crack closure is observed as a thing with a possibility that the influence of change of the stress level and a stress ratio, etc. to the crack growth behavior can be explained, and until now various researches have been done. Although there is a method using the strain gage as the dynamic measurement method required for the elucidation of a minute fatigue crack, in respect of generating of minute fatigue cracks being directly contacted to a measuring object thing, and there is a problem in durability or measurement of the crack growth behavior, it may not necessarily be effective. Then, its attention was paid to the magnetostriction effect which is one of the magnetic actions of a ferromagnetic substance. Measurement of micro fatigue crack information under dynamic load without requiring a simple device and contact with the object was carried out and the change in the magnetic field around the test piece due to the magnetostrictive effect was measured using a coil. We investigated micro fatigue crack information from the information.

Ceramic matrix composites (CMCs) have attracted much attention as lightweight and ultra-high heat-resistant materials for aircraft gas turbine engines. Since the fracture process of CMCs is very complex, a non-destructive method with high accuracy has been desired for safe use of CMCs. Many kinds of non-destructive methods have been proposed for damage monitoring and the direct-current potential difference method (DC-PDM) is known as one of the best techniques to identify small cracks and voids not only in monolithic materials but composite materials. In this study, DC-PDM is applied to non-damaged and high-temperature-fatigued specimens of CMC and its applicability is examined. Although the resistance depends on the location of the specimen, the fatigued specimen showed very high values. This result suggests that DC-PDM is applicable to high-temperature fatigue damage of CMC.

As a method for evaluating the pitching fatigue characteristic on the gear tooth surface, a roller pitting test is commonly conducted. In this test, a pair of cylindrical test pieces are under the rolling-sliding contact condition with high surface pressure. Conventionally, the test piece was removed from the testing machine during the test and the damage was observed. However, there are possibilities that different parts may come into contact with each other due to installation errors. Therefore, it is difficult to observe accurate damage phenomena. Therefore, in this study, we constructed a system for observing the cylindrical surface on a roller pitching machine and showed its usefulness. We succeeded in observing the surface of pieces at 140 time, magnification.

This study develops the indentation method to evaluate transversely isotropic viscoelasticity. Firstly, it is shown that rigid cone indentation for transversely isotropic elastic materials and transversely isotropic viscoelastic materials have the same coefficient that is function of ratio of Young's modulus. Next, the indentation force and the penetration depth curve, F - h curve, on transversely isotropic elastic material are analyzed by finite element method. As the results, the coefficient of loading part of the F - h curve can be expressed as a function of ratio of Young's modulus. Finally, this indentation method is applied to measure anisotropic viscoelasticity of plastically deformed polycarbonate.

When an electrodeposited copper or nickel foil is subjected to a cyclic loading, grain growth occurs in the foil. If the relationship between the grain density, stress amplitude and number of cycles has been calibrated beforehand, it is possible to measure the stress amplitude based on the grain density. Since the thermal recrystallization occurs in the foil when the ambient temperature rises, the upper limit of the ambient temperature is limited to 80 oC and 250 oC for the copper foil and the nickel foil, respectively. In this paper, the possibility of stress measurement at higher temperature was examined by applying nickel alloy foil. First, the nickel alloy foil was heat treated under various conditions. Then the grain size was analyzed using EBSD in order to check whether grain growth occurred. Moreover, the pulsating tension tests were carried out under 350 to 450 oC, and the grain size was also analyzed. It was revealed that the nickel alloy foil was recrystallized at a temperature of 350 to 450 oC. Moreover, the grain growth due to cyclic loading could also be confirmed under 350 to 450 oC. Therefore, the possibility of stress measurement by nickel alloy foil under high temperature environment was suggested. A calibration equation for stress measurement was proposed based on the grain size equation proposed for the recrystallization.

In the ductile crack propagation phenomenon, the plastic strain distribution differs between the surface and interior of material because of the difference in stress field. Furthermore, the interior of material is controlling factor of the crack propagation. However, digital image correlation (DIC) cannot be applied in the interior of material. Hence, it is difficult to measure the internal plastic strain distribution. We measured grain orientation spread (GOS) and dislocation density by electron backscatter diffraction (EBSD) measurement and electron channeling contrast imaging (ECCI) to obtain plastic strain maps near a notch in pure nickel as a FCC model sample. In particular, we obtained quantitative relationship among GOS value, dislocation density, and plastic strain on the surface of specimen, which were obtained by EBSD, ECCI, and DIC, respectively. After obtaining GOS value–plastic strain and dislocation density–plastic strain relations on the surface of specimen, the plastic strain distribution in the interior of specimen was also determined by measuring the GOS value and dislocation density. Both of the GOS value and dislocation density showed a linear correlation with plastic strain on the surface of specimen. Furthermore, the dislocation density–plastic strain relation showed a relatively smaller deviation than the GOS value–plastic strain relation. In the interior of specimen, as the distance from the notch tip became longer, the plastic strain determined by the GOS value and dislocation density monotonously decreased.

This study aims to evaluate coating adhesion, i.e. the interfacial strength of coatings and thin films by using Laser Shock Adhesion Test (LaSAT). This method uses strong elastic wave induced by pulsed laser ablation. The elastic wave causes the coating delamination, when the maximum stress wave reaches the critical value (interfacial strength). In parallel, the out of plane displacement is measured by using a laser ultrasonic interferometer. The timing of delamination can be detected by the correlation coefficient calculated with a series of the out-of-plane displacement velocity waveform. Furthermore, computation of elastic wave propagation using FDTD (Finite difference time domain) is carried out to estimate tensile stress developed at the coating film/substrate interface. Based on the above results, the interfacial strength is estimated. In addition, the interfacial adhesion durability is evaluated by using repeated laser irradiation based on the above method (LaSAT). In this method, repetitive lower stress loading is applied to the interface. We evaluate the cycle number of repeated laser irradiation up to coating delamination, so that it may estimate the interfacial strength (adhesion) durability. It was found that delamination occurs at lower loading than the interface strength. This result may be useful for adhesion durability, when a coating is used in long time and subjected to cyclic loading.

A method for evaluating the stress triaxiality of thin steel plate is studied. Three-dimensikonal displacements and the surface strains of high strength steel specimen are measured using a stereo image correlation method. The measurement is performed from both sides of the front and back to evaluate not only in-plane strains but also through-thickness strains. From the mesured strains, the principal stresses are calculated based on the total strain theory, and then the stress triaxiality is obtained. Experimental results show that the stress triaxiality history can be obtained by the proposed method.

This study investigated the tensile deformation behavior of porous polymer membranes (polytetrafluoroethylene; PTFE and Polyvinylidene difluoride; PVDF), which are used for water purification. The membranes have micron and sub-micron pores with open-cell structure. The surface and cross section of the membranes was observed by FESEM to carefully investigate the microstructure (cellular structure). Uni-axial tensile tests were carried out, and it is found that the membranes underwent elastic deformation and plastic deformation. To investigate microscopic deformation behavior, in-situ observation during tensile deformation was conducted using SEM. Based on this observation, we discussed the mechanism of elasto-plastic deformation behavior of polymer membrane. In order to establish a mechanical model for such a deformation behavior, finite element method (FEM) was employed. In this FEM model, random pore structure was created to mimic open-cell structure of the present membrane, and we discuss the deformation behavior of membrane.

Model experiments were conducted using paraffin wax in order to clarify a developing process of quenching stress in thermal barrier coating. A droplet of melted paraffin wax was dropped onto a circular metallic substrate, and a quenching strain generated at the substrate back surface was measured during solidification and adhesion process of droplet. Effects of several experimental variables, including substrate temperature, droplet materials and impinging velocity, were examined focusing on the developing process of quenching strain and fracture behaviors of solidified coating. A series of the model experiments revealed that the quenching strain was affected by substrate temperature, thickness of film and material properties of droplet, such as Young's modulus and coefficient of thermal expansion. During the solidification and adhesion process, cracking and delamination of the solidified coating were taken place depending on the substrate temperature and paraffin materials.

Displacement distribution in circular shaft specimen of steel during tensile test was measured using digital image correlation (DIC) method. Video image of the specimen surface was continuously taken during tensile test and static images were converted from the movie file after the test. Distributions of strains in axial and in vertical directions were obtained from the displacement distribution and also diameter of the specimen was estimated based on strain distribution in vertical direction to the specimen axis. Distributions of strain and diameter of the specimen were measured during whole tensile test and material properties were derived.

In the paper, the small drop-weight testing machine was developed on the basis of electromagnetic induction phenomena. The electromotive force generated in the coil near the specimen was measured when the small impactor containing a neodymium magnet and having mass of 0.36, 0.44 or 0.63 g dropped on the specimen. The impact force and specimen deflection were analyzed from the measured electromotive force based on the facts that the electromotive-force intensity is proportional to the impactor velocity and the electromotive force variation is dependent on the impactor position according to Faraday's law of induction. The validities of the testing machine and measurement system were confirmed by considering the experimental results of the falling drop tests for the rubber plates.

Thermal barrier coatings are necessary for making greater heat-resistance materials based on metal substrate. In this study, a test system to measure elastic moduli, modulus of longitudinal elasticity E, of shear elasticity G and/or Poisson's ratio μ, is developed and its availability is experimentally confirmed. The longitudinal modulus (Young's modulus) E of thermal barrier coating was measured under the high temperature environment up to 1000°C. The rectangular section bar specimens which have two-layer coating consisting of a metallic bond coat and a ceramic top coat were used in the experiment. E values of each layer were calculated from the natural frequency of the specimen applying the multi-layer beam theory for the flexural free vibration. In this system, the natural frequencies of both bending mode and torsional mode of vibration can be measure easily by impact sound of one specimen. So that the natural frequency fT of torsional mode was measured by FFT analysis of different impact sounds obtained from a variety of impact point on the specimen at a room temperature. The experimental results are compared with the results of FEM analysis for the natural frequencies of each mode of vibration.

Deterioration of large infrastructures that were constructed in the period of rapid economic growth is becoming a big problem in Japan these days. One method to measure the deterioration is to use optical method that can measure deformation or strain of a structure from a position far from the structure, and the other is to use a robot that moves on the surface of the structure and measures the deterioration of it. When one uses a mobile robot to inspect the deterioration, it is necessary for the robot to detect its own position. The paper describes basic experiments on the detection of position of a mobile robot. Two rotary encoders are used to measure the position of the robot as a function of time. When the robot moves by 8.7 m in x-direction, the error Δy of the position in y-direction was about ±5 cm. In circular motion, the radius of real trajectory of the robot is approximately equal to the objective radius, whose error was 0.7% on the average.

Quantitative discussion on the performance of the measurement system including the operation skill based on the reference is needed from the viewpoint of establishing the traceability of measurement. For acoustic emission (AE) method, a specimen which can control behavior of AE occurrence seems to be useful for standardization. In this study, possibility of realizing the standard specimen for AE measurement was examined. Specimens containing regions of different stress concentration resulted from different shape holes were made by stereolithography and those were subjected to tensile load. It was demonstrated that AE events at the intended location could be occurred for the specimen with different shape lozenged holes to change the degree of stress concentration. It was also found that drop-like holes for changing the degree of stress concentration rapidly are useful to generate AE events at the intended location and timing. From these results, possibility of realizing the standard specimens fro AE method was indicated.

In this study, a 3D measurement projection mapping system for displaying displacement distribution on a measured object using a grating projection method is developed. A grating projection method is often used as a high accurate 3D shape measurement method. It is also possible to apply the 3D shape measurement system to measure a wide and smooth curved surface such as a sheet metal processing. In this case, operators take much effort to recognize the spatial coordinates of some problem from the measured result displayed on a monitor. Therefore, authors have developed a rapid projection mapping method for the measured 3D shape and displacement distribution of a specimen. The developed system was applied to a 3D measurement of a deformed plate. The architecture and the experimental results are shown.

Biomaterial is a material that is embedded in human body and the most of that are used metals because of its high mechanical property. In some of the biomaterials, surgery is required to remove after complete recovery so that it imposes high surgery cost and physical and mental pains to patients. The development of a magnesium based bioabsorbable material that is not required surgery and safely vanish in human body has attracted attention. On the other hand, a practical use of Mg has some problems and one of them is low corrosion resistance. Since Cl- ion contained in body fluid causes corrosion under biological environmental, Mg has greatly low corrosion potential in metals and easily corroded in human body. It is also concerned about secondary damage such as refracture of bone by keeping it in the body, and it is required to vanish immediately after recovery, so we controlled corrosion behavior of Mg with coating Ti and PLA. Mg and Ti have a large potential difference so that corrosion proceeds immediately by galvanic corrosion and Mg coated with Ti (Mg/Ti) dissolved for a day. PLA is a bioabsorbable polymeric material and it is already practical use as a bioabsorbable material. PLA dissolves gradually by hydrolysis so that it can suppress corrosion until hydrolysis. We resulted that Mg/Ti coated with PLA remained for 20 days, so PLA could suppress corrosion of Mg/Ti.

Magnesium (Mg) would being attracted as biomaterial in the stent application since Mg had have to be biocompatibility and adjustment in body even though it has the disadvantage properties of low corrosion resistance and strength. For the improvement of the surface morphology we had tried to deposit pure Mg by a resistance heating deposition in vacuum on Mg 99.9wt% ribbon. Some of the specimens were deposited with the thickness of Mg as 1 μm in the deposition. All specimens were immersed in 0.9%NaCl at 37℃ for 0, 48 and 120 hours and then carried out tensile test and we’ve got the stress-strain relationship. Several areas in the specimens had been inspected the surface roughness with an atomic force microscope. It resulted that tensile strength (TS) of Deposited ones was higher than that of As-received. The difference of TS between the As-received and deposited ones were 36 MPa for 48 hours’ immersion and 11 MPa for 120 hours’. Yang’s module of the specimens immersed for 120 hours was lower than those of immersed for 0, 48 hours. The fracture of the specimens immersed for 48 hours is in ductile with crack propagation from the inside but the fracture immersed for 120 hours is from the surface to edge. Since average surface roughness of deposited ones was smaller than that of As-received, it shows that the surface quality of As-received ones is improved with depositing Mg. Nevertheless, the relationship between surface quality and strength in corrosion could not be clarified because the adhesion at the interface of deposition was insufficient due to less activation of the Mg ribbon’s surface. It might be important for this research to reconsider surface preparation before depositing Mg.

The bottom-up-type microstructural optimization of the HAp/collagen composite fibers would enable the creation of the artificial bone mimicking the bone microstructures. In the present study, the effect of the preparation condition on the mechanical properties of HAp/collagen composite fibers was evaluated by means of the micro-tensile tests. Here, the collagen fibers were prepared by the bio-inspired method, where the fibrosis and the cross-linking are generated at the same time. The HAp particles were deposited on the collagen fibers by the biomimetic deposition method, where the collagen fibers are dipped into the pseudo body fluid alternatively. In the present study, the cross-linking agent concentration and the alternative dipping time were varied. In addition, HAp/collagen complex fibers were coated with the adhesive protein before the HAp deposition process. As a result, the coating with the adhesion protein decreased the tensile strength of the HAp/collagen complex fibers prepared under the optimum condition within the range covered in this paper. It was suggested that the adhesive protein would act as the additional cross-linking agent, resulting the excessive cross-linking. Therefore, it can be expected that the coating with the adhesive protein after the insufficient cross-linking could maximize the tensile strength of the HAp/collagen composite fibers with the adhesive protein coating.

The indentation test has been widely used to evaluate mechanical properties of industrial and biological materials in many studies. In this study, we obtained an analytical solution of axisymmetric contact problem of viscoelastic layer bonded on rigid substrate indented by flat-ended cylindrical punch using elastic-viscoelastic corresponding principle. The relaxation indentation tests were conducted for silicon rubber, Echo PAD which is a soft material used for elastography, and articular cartilage of bovine femoral head. For articular cartilage, fresh articular cartilage was treated by collagenase after a relaxation indentation test and was then used again in same test. The viscoelastic models in this study were selected as three-element model (standard linear solid model) and five-element model (generalized Maxwell model) and viscoelastic parameters of the models were determined by fitting the analytical solution to applied load varying with time collected from the relaxation indentation test. As the results, it was suggested that the five-element model was more appropriate than three-element model to reproduce the behavior of relaxation indentation of silicon rubber, Echo PAD, and articular cartilage. Furthermore, the viscoelastic parameters of treated articular cartilage decreased sufficiently compared with those of fresh articular cartilage. From these results, it was suggested that the method of evaluating the time-dependent mechanical properties of articular cartilage based on the analytical solutions of the relaxation indentation test obtained from this study could be a useful tool for evaluating the state of degenerated cartilage.

Bone tissue with hierarchical structure is regarded as complex structure consisting of organic collagen and inorganic hydroxyapatite (HAp). Using the component analysis method called Raman spectroscopy, the change in Raman shift was measured while applying load to bone tissue, and the relationship between stress and Raman shift was investigated. In addition, the Raman shifts were measured by statistical process based on the Raman images. The specimens with the sizes of 10 × 2 × 0.5 mm were cut out from 23 m. o. bovine femoral diaphysis, where the longer edges of specimens are aligned to the parallel to the femoral axis. Decalcified specimens with 10% formic acid (CH₂ O₂) for 4 hours were prepared. Strain gauges were attached to bovine cortical bone specimens, and Raman spectrum was measured while applying tensile stress. The Raman shifts were calculated by averaging obtained peak shifts at all measurements point. As the results, the mechanical behaviors of collagen matrix in demineralized bone were found by Raman spectroscopy.

The extension of healthy life expectancy is required. Locomo prevention is being promoted to maintain motor function. Locomo is an abbreviation for Locomotive Syndrome. Japanese name is exerciser syndrome. In other words, it is a state in which the movement function has deteriorated due to the failure of the exerciser. The muscles of the lower limbs, which are important during walking, are the quadriceps muscle that extends the knee and the bending hamstring. The quadriceps muscle has the function of extending the knee. Hamstring has the function of bending the knee. A handheld dynamometer is used for general practice. However, this measurement does not consider the joint angle. Therefore, accurate muscular strength cannot be measured. In this study, we developed a measuring device capable of measuring muscle strength under the joint angle where muscle strength is maximized. In addition, we aimed to develop and propose a portable measurement device that can be carried. As a result, muscular strength of the quadriceps muscle and hamstring could be measured at the knee joint angle that demonstrated maximum muscle strength. In addition, it was suggested that it is important to match the position of the knee pad with the position of the knee pad.

Catheter insertion is a sensitive operation largely depending on tactile senses of the doctor. Although several kinds of force measurement systems attached in the catheter have been proposed, the measurement of the force during operation should be measured at the finger for evaluation of the tactile senses. In this study, we developed a film type tri-axial stress sensor that can be attached to the fingertip. An electro-conductive polymer in polythiophene series was used for the pressure sensitive layer. The conductive polymer material has a characteristic that the electric resistance in the thickness direction decreases under the compression. This type sensor is thin and flexible therefore it can be expected to directly measure the contact stress at the fingertip. In this experiment, the contact stress is measured under during catheter guide wire insertion motion. The contact stress vector including vertical and the plane directional components were detected at the gripping area of the wire. The motion trajectory of the finger in the catheter insertion was analyzed in a motion capture system. As a result, changes of the contact stress according to forward, backward, and rotation in the catheter operations were observed during insertion tests. It is possible to evaluate the catheter operation by means of the tactile sensing. Also, this measurement system can be applied not only to evaluate the skill of catheter operation but also to use for training the operation.

Balloon catheters have successfully been used in both cardiology and cardiovascular surgery. However, it has been reported that the fracture of a balloon catheter can be occurred when it is inserted into a small blood vessel with severe arteriosclerosis and stucked due to the calcified endothelial. It is therefore important to understand the tensile deformation and fracture behaviors of balloon catheters. In this study, the tensile deformation behaviors of two different balloon catheters were characterized and the theoretical models were developed to predict the load-displacement curves.

In this study, we study ultimate swelling characterized by limiting chain extensibility of swollen elastomers. Limiting chain extensibility is introduced into the Flory-Rehner theory. The derived inequality allows for analysis to provide an ultimate value of swelling ratio. This ultimate value is not exceeded at equilibrium swelling regardless of the set of material constants. Under uniaxial loading at equilibrium swelling, deswelling can occur even in tension.

When tumor cells metastasize, invasion of cells plays a major role. The tumor cells initiate invasion by generating force and changing the physical structure of the extracellular matrix (ECM) surrounding the tumor. However, the detail process of changing the structure of the ECM has not been elucidated. At this time, measuring the mechanics field generated in the ECM is an important way to understand behavior of tumor cells in 3D. Therefore, in this study, spheroids, which are the source of the invasion as a tumor cells, were embedded in a collagen gel, and the deformations of the collagen gel surrounding the spheroids were measured. Using the DVC method, the matrix deformations around spheroids were measured by tracking the 3D positions of fluorescent beads embedded in the collagen gel. To photograph the initial state of the ECM, we added tritonX-100 to the spheroid at the end of the experiment and photographed the state of no stress from the spheroid. In addition, we calculated the divergence of the deformations field and discussed on density change of ECM. As a result, it was found that spheroids systematically generate the deformation field and change the density of ECM. It was suggested that invasion occurs in the low density part.

In this study, the compression tests were performed for white and gray matter in cervical spinal cord of bovine to evaluate thire resistance against the compressive damage. Then the compressive damage rate C_d was measured on the basis of the compressive load-time diagrams. The value of C_d increased with increase in compresion rate D_R, and the C_d value in the gray matter was greater than the one in the white matter. The larger C_d was comfirmed in the longer compression holding time in D_R= 50%, while C_dvalues did not show large variation in D_R= 30 and 70%, becase the tissues exhibits the elastic state totally in D_R= 30% (small compression) and the elastic recovery did not occure in D_R= 70% because of the huge damage of the tissues. In the longer unloading holding time, C_dvalues became smaller becase of the visco-elastic behavior of these tissues.

External forces on the skin surface are known to cause a pressure ulcer. A compressive force has been studied widely, but a shear force has not been studied enough. The aim of this study is to model and simulate the shear deformation behavior of layered tissues, especially subcutaneous tissue because it deforms easily when it is subjected to the shear on the skin surface. At first, we formulated the kinematic relationships for a simple shear to simulate the deformation behavior of the subcutaneous tissue as a representative one among the layered soft tissues. Secondly, we obtained a shear component of the stress as a function of the strain components. Then we postulated a Mooney-Rivlin hyperelastic model to describe the stress-strain relationship of the shear component explicitly. We also formulated a linear viscoelastic model by assuming a Prony function for a stress relaxation function. Based on the experimental results for porcine soft tissue, which consists of skin, subcutaneous tissue, tendinous tissue and skeletal tissue, we identified parameters in the Prony series of stress relaxation function. Finally, we simulated the time history of stress in the subcutaneous tissue for the simple shear. Our model described a nonlinear time history of the shear stress. The insufficient nonlinearity may be attributed to discontinuous slides which occur simultaneously with the shear deformation in the subcutaneous tissue.

A methodology of accurate fracture estimation for carbon fiber reinforced plastic (CFRP) tank is presented in the framework of meso-scale mechanics, where carbon fiber bundle and resin are distinguished. Its validity is proven through an experiment employing cross shape specimen representing fiber bundle situation in CFRP layer of the tank. The specimen is manufactured by filament winding machine to form crimps of fiber bundles crossover by right angle. Its mesoscopic structure of fiber bundle and resin is precisely modeled for the finite element analysis. Highly non-linear material model of resin strength has been applied to predict breakage load and elongation of the specimen under biaxial tensile test. We have elucidated strain-rate dependency and tension-compression asymmetry in resin strength, and transverse strength of fiber bundle govern the fracture process of the specimen.