Pipe wall thinning is an important issue for aging management of nuclear and fossil power plants. The Japanese Society of Mechanical Engineers (JSME) published a guideline on pipe wall thinning management in 2005 and management codes in 2006, which is based on inspection using UT. In JSME, research committee for the improvement of pipe wall thinning management has been held since 2008, where state of the arts technical knowledge was investigated. In this committee, research for new technical knowledge for the mechanisms of wall thinning, evaluation methods, new inspection methods etc. Regarding the evaluation methods, how it is reflected to the management codes is considered. Risk based management and criteria for local wall thinning are also investigated.

Pipe wall thinning is an important issue for aging management of nuclear and fossil power plants. The Japanese Society of Mechanical Engineers (JSME) published a guideline on pipe wall thinning management in 2005 and since then, thinning of pipe wall thickness has been managed based on non-destructive inspection of pipe wall thickness. In JSME, research committee for the improvement of pipe wall thinning management has been held since 2008. In this committee, research and surveillance have been conducted on concerned technical area including wall thinning prediction and inspection method to revise a technical knowledge report attached to the JSME guideline. This paper summarizes recent advances of technical knowledge regarding flow accelerated corrosion, liquid drop impingement, and non-destructive inspection.

As one of the major activities of the JSME research committee for the improvement of pipe wall thinning management, latest knowledge concerning pipe wall thinning phenomena and state of the art inspection technologies of wall thickness have been surveyed and reviewed. Although a complete management of pipe wall wastage consists of prediction, inspection, and evaluation, survey of the evaluation part has been running late compared to the prediction and inspection parts. Survey of “Risk Based Maintenance” and “Acceptance Criteria for Localized Metal Loss” was recently initiated in the research committee. This paper summarizes scope and status of the survey.

In JSME, research committee for the improvement of pipe wall thinning management has been held since 2008. In this committee, research and surveillance have been conducted on concerned technical area including wall thinning prediction method, inspection and monitoring of wall thickness, criteria of pipe integrity of local wall thinning, etc. Under this committee, new working group called “Management Rule Revision WG” was set up to review practical application and standardization of the developed relevant technique, especially prediction method in 2015. It is expected in the future, that the pipe wall thinning management in domestic power plant will be rationally improved by the revision of management rule scientifically and consequently resulted in further enhancement of safety level in power plants.

In domestic nuclear and fossil power plants, pipe wall thinning is managed based on residual lifetime evaluation calculated from wall thickness measurement results. While in other countries, referring to the basic studies on flow-accelerated corrosion (FAC) conducted from the 1970's, prediction method of FAC rate was introduced into the management from around 1990's which resulted in optimization of pipe inspection, repair and replacement. In JSME, research committee for improvements of pipe wall thinning management has been established since 2008 and now is in its fourth phase. For the future introduction of prediction method into the management in domestic power plants, the following items were surveyed and presented as references; management with predicted software in foreign countries, information from International Conference on FAC, and related activities in the IAEA FAC coordinated research project (CRP).

We are studying about a clamp-on ultrasonic flowmeter for low pressure gas. We tried to measure the flow velocity of atmospheric pressure air. We showed the method of separating the ultrasonic wave which propagates internal air, and that propagates a metal pipe. With this method, we detected the ultrasonic wave which propagates internal air. We measured the flow velocity of air by measuring the propagation times of the ultrasonic waves. We are trying the further improvement of the measurement accuracy.

Recently, necessity of energy saving is more increasing in the industrial field with relation to energy cost increase. Measurement of steam flow rate is indispensable for a performance diagnosis and an energy solution in facilities such as factories and power plants. However, installation of sensor for steam flow is not generally enough. The industrial facilities needs to be out of operation temporarily, in the case of installation of conventional flowmeter such as orifice type and vortex type. Because steam pipes are necessary to be cut for the installation. Accordingly, clamp-on type steam flowmeter, of which installation does not require pipe-cutting, is hoped to be developed. Ultrasonic sensor has certain degree of possibility for steam flow measurement. On the other hand, there are such problems as ultrasonic inlet to a pipe and operational condition of temperature, to be solved. Therefore, we devised “heater method” for steam flow measurement. A circumferential heater is attached to the outside of a tube. Then, axial temperature distribution on the tube outside is measured. Steam velocity is analyzed on the basis of the temperature distribution, considering heat transmission in the pipe. The sensor is heat-resistant and possible to measure high temperature fluid, because it is comprised of the heater, thermocouples and insulator. It is necessary to solve physical phenomenon such as temperature boundary layer and heat transmission in the pipe in case of area heating, to develop the method. This proceeding reports measurement theory confirmation using air and steam flow rate measurement by the heater method.

In the cutting and grinding of ultra-precision, higher demand such as high precision, improved surface finish and so on have been required increasingly as our market situation. To meet those demands, high speed machining is quite effective through our reserch experiences, and the technology can also improve the productivity and the life of small tools. The actual theme is how we apply this technology for our development and improve the efficiency of our factory state dramatically as challenge. In order to realize the high-precision and high speed machining using small tools in the field around Max.100,000min^-1, we have developed the "ABT-1000". This spindle have a high rotational force with low energy consumption and a small size body. Also it has a sophisticated monitoring function which is useful to detect the spindle speed. This paper introduces the features of this "ABT-1000".

The paper describes a brief introduction of our developments for robotics joint with variable and designable stiffness in mechanical basis. The core mechanism is a classical differential gear system (DGS) uses as a 2 inputs 1 output mechanical transmission. It gives us a dexterous motion of the joint when taking a passively acted input and an actively driven input. The planetary gear system (PGS) is one of a DGS we have employed in our robotics joint. The artificial finger equipped with a PGS in its MP joint acquires a shape-fitting ability when it takes envelope grasping of unknown shape objects. The artificial forearm equipped with a PGS in its wrist joint allows us under-actuated control of angle and stiffness of the three rotary axes. The DGS, a mechanical module comprising PGS, has utilities in wider range of mechanical system having a lot number of DOF like robotic joints. This paper shows a typical example of application of the DGS in a robotic gripper having serially connected multi joints.

The various restrictions exist in a design of welfare equipment. Therefore, I have developed welfare equipment using link mechanisms. Then I describe about a development of welfare equipment using original link mechanisms. A wheelchair of multiple functions is to use some mechanical links, and it's possible to be transformed into 4 styles. A humanoid hand for robot and artificial arm achieves various movement by 1 actuator by using an original mechanical link, it is called harmonic link mechanism. Geta robot is to use the original shape on its foot, and it can walk with knee stretch like a human being. This paper is described about the link mechanisms and outline of these welfare equipment.

Since computer technologies have been progressed as shown in the recent advancing in artificial intelligence (AI), utilization of networks has been variated to generate a new idea, in which the network treats not only information but also connects various gadgets to perform several tasks. We have presented a coined word informotion by means of assembling information and motion to establish a new network informotion network system (INS) composed of a great number of various actuators. In order to realize INS, we need various new actuators, energy supply method and a new control method. For the last issue, we discuss that we will unify several theories such as self-organization, artificial life, swarm intelligence, harness, multi-agent system and tacit learning to control INS behavior.

The purpose of this study is to develop power assist device, which is easy to use like normal clothes and does not restrict movement, and portable air supply system. User can be assisted by wearing this one on which the pneumatic soft actuator, which has a high power weight ratio and a light weight, is put. The developed air supply system, which can retrieve compressed air from an actuator, is effective to decrease energy consumption. This air supply system is effective to downsize whole system. In this paper, outlines of the developed power assist wear without exoskeletons, and portable air supply system are described.

Ultrasonic vibration can generally be excited by piezoelectric materials and can propagate in elastic medium coupled to them. Some researchers have applied ultrasonic vibration to realization of tactile displays. Users touch display surface on which the vibtation is excited. Under the touch, the friction between the surface and the user's finger can be reduced, because there is air gap which is induced by the ultrasonic vibration (squeeze film effect). The tactile display can be configured by controlling this friction reduction process in the time domain. The application of surface acoustic waves (SAWs) to tactile displays has also been proposed. In the case of SAWs, the operating frequency is higher and the friction reduction can be induced by intermittant contact. A prototype was fabricated and demonstrated.

Creation is to produce the one which didn‘t exist by now and a fact for the first time , and it's invention to contrive the way to embody the methods and the means. And I think innovation occurs when bringing a paradigm shift to society as a result of the invention. How is it performed with the creation which leads to this innovation? How are " notices " and "flash" which are the starting point? We have interest to such proposition. Because “notices" and "flash" are a source of creation, it's a natural thing ,but hope is had for formulation of the activity that “notices" and "flash" are promoted as well as the activity that creation is promoted in recent years.As one of the activity, a document (Shimizu, 2015) is introduced about Honda WAIGAYA which is the group creation way which promotes "flash" and “notices" by expressing the opinion each other and arguing essentially freely noisily by everyone and create new matter and concept through the activity.So, I have investigated how the technology which is often learned about was born by going back to incunabula, and the case of innovation by Honda. "Flash" and “notices" which are a source of creation are considered about the environment, the condition and an element by finding the common items from these cases.

“Waigaya” has been seen as a prominent mechanism to realize synthesis of design, which leads to actualization of brand new product. Though its efficacy has been discussed mentally or qualitatively, there has never been any theoretical explanation. This paper attempts to understand efficacy of “Waigaya” based on General Design Theory as a theoretical foundation. As a result, it is found that quite large part of “Waigaya” could be understood through General Design Theory, whereas there are some fundamentals that remain unsolved or mentally understood.

The Japanese terms, such as "Y-gaya" of Honda and "Suriawase", attract attention recently as "collaborative creation work considered from zero in a group. "Participating member's common actual site experience has large role in "group creation" for evoking "flashing" with "finding out". "Suriawase" was effective at manufacturing shop floor in Japan. Group who has done on-site experience and understanding of objective or situation, as for this "Suriawase", good Output(s), such as result of high quality manufacturing shop floor and elaborate design investigation result, were obtained. Recently, Virtual Engineering environment progressed greatly and it became time when virtual experience etc. can be performed convenient. Therefore, more people can understand "actual site", "actual part", and "realistic" experience, and turn out in many fields can be effectively "common in thinking". Virtual Engineering environment, "Suriawase" and "Y-gaya" are larger than before, and the limits of activity spreads. As a result, many innovations may be produced. Put expectation and introduce them.

I considered how to use an engineer's training, a setup of a development goal, and a concrete tool in the viewpoint of "the Honda type Wigaya" by making aerodynamic development of F1 into an example.Since body development of F1 was dividing and developing each component, it was in the situation where I have not taken cooperation of the technology which influences mutually.Although the aerodynamic team was a specialist in an airplane, there was no knowledge about the characteristic for vehicles.Similarly a body development member did not have the knowledge which evaluates aerodynamic appropriately.Moreover, calculation tool Computational Fluid Dynamics (CFD) of the aerodynamic was not a reliable level.Even if there is special knowledge and it performs "Wigaya" with a member with little knowledge of other sections, it cannot raise the level of an entire team, either and does not become the technology out of which a result comes, either.As a measure, each special-field-of-study member created the curricular material which teaches a concept plainly for the person of its other posts, and repeated PR mutually.When these preparations were completed, I increased free technical debate.The engineers who deepened the mutual understanding gained new development approach, the increase in a development staff, and improvement in quality.

In this paper, we focus on IoT/M2M standardization trends and IoT communication technology. About the standardization trends, we organize international standardization activities and analyze their aims. Next, as the communication technology, we introduce the concept of symbiotic ecosystem for realizing sophisticated social infrastructure, the data catalogue technique and the wireless communication technique for ensuring the connectivity of IoT devices.

In recent years, the practical application of IoT / M2M is progressing in various fields. In the near future, 1 trillion of sensor nodes in Japan is installed. There are some technical problems to dissemination the IoT / M2M. One is a wireless technology. Wireless technology has required a special technology, in recent years, inexpensive and easy-wireless equipment made possible by the advent of the communication module. The other hand is the power supply technology. Energy supply for operating the devices are wired. In this report, we attempt to discuss the wireless technology and the power supply technology and technical issues necessary for the realization of the IoT / M2M.

This paper presents the history of the development of the management system for an informationally structured environment named Town Management System, TMS. The development of TMS was started in 2005 in the project named Robot Town Project. We are continuing our efforts for improving the performance and enhancing the functions of the TMS so far. Recently, we launched a new town management system named ROS-TMS ver. 4.0, which combines TMS and ROS to utilize the high scalability and a plenty of resources of ROS. We also introduce a new informationally structured platform named Big Sensor Box, B-sen, in which a variety of sensors are embedded and service robots are operated according to the structured information under the management of the ROS-TMS.

We examined the viscoelastic behavior of gels and chose the material model for useful and simple numerical simulation using finite element method. To examine the viscoelastic behavior of gel, we performed the creep tests including large strain and the dynamic mechanical analysis of gels. From the results of these experiments, we found that the viscoelastic behavior is independent of strain level. Considering the results of the experiments, the viscoelastic model proposed by Simo was chosen. The material constants of chosen model were identified with the data of the experiments. Moreover, we perform some experiments and numerical calculations using the chosen material model and the identified material constants. From the results of the numerical calculations and the experiments, it is found that the chosen material model and the identified material constants have good reproducibility and versatility in wide time scale and strain range.

Singular electric displacement fields occur around the vertex of interface in a piezoelectric material joints under loadings. In the previous study, influence of load conditions on singular electric displacement fields in the piezoelectric material joints were investigated to apply for engineering. In this study, some characteristics of singular electric displacement fields in an outside domain of piezoelectric material joints were investigated by using 3-dimensional finite element analysis. Influences of loading conditions on singular electric displacement fields are discussed . Singular electric displacement fields in an outside domain of piezoelectric material joints occur around the vertex of interface in it under loadings. Singular electric displacement fields are infulenced by tme change of the stress to depend on a piezoelectric material joints.

Ferroelectric thin films are using the actuators and sensors in medical devices. Therefore, developments of biocompatible novel lead-free piezoelectric materials are required. In previous study, novel lead-free piezoelectric materials, which were solitary crystals ABO₃ and complex crystals (A,A’)BO₃ and A(B,B’)O₃ of perovskite-type oxide, were discovered by employing first principle calculation based on density functional theory (DFT). In this paper, to support the fabrication of novel lead-free piezoelectric thin films, the phase diagram was predicted through first principle calculation. Firstly, stable crystal structure of perovskite oxides was evaluated. Secondly, total energy, spontaneous polarization, elastic compliance and electrostrictive coefficient were calculated from crystal structures. Thirdly, the free energy function with consideration of misfit strain was approximated from total energy and spontaneous polarization of asymmetric crystal structures. Finally, the stable thin film phase with minimum energy was investigated by employing the approximated free energy function. The developed prediction procedure was applied to existing materials PZT and novel lead-free piezoelectric materials. Especially, the effect of material composition on phase diagram was discussed.

Multiferroic composite materials consist of ferroelectric and ferromagnetic phases. The interference between these two phases generate the ME effects. The ME effects strongly depend on inhomogeneous microstructure. In this paper, the generating mechanism of magnetoelectric (ME) effects was numerically investigated for polycrystalline multiferroic composite materials. A multiscale simulation based on asymptotic homogenized theory was employed for scale-bridging between macro and micro structures. Physical properties of ferroelectric (FE) and ferromagnetic (FM) were allocated to every element in micro FE model by using a random generator. The crystal orientations were arranged in consideration of domain switching system of both phases. The macrostructural physical homogenized properties were analyzed and the influence of volume fraction of FE phase were investigated. The microstructural strain distributions were investigated when an external magnetic field was applied to the macrostructure. The overall frequency distribution of microstructural strain exists in equilibrium. It has a center at zero and symmetry against positive and negative sides. However the strain distribution in only FE phase shifts to positive side, and that in FM phase shifts to negative side. It was found that the shift of microstructural strain distribution in each phase and macrostructural piezoelectric and piezomagnetic constants are dominate factors of ME effects. The combination of these factors creates the maximum peak of ME coefficients.

As is well known, a sub-domain method is often used in computational mechanics. The conforming sub-domains, where the sub-domains are not separated nor overlapped each other, are often used, while the nonconforming sub-domains could be employed if needed. In the latter cases, the integrations of the sub-domains may be performed easily by choosing a simple configuration. Then, the meshless method with nonconforming sub-domains is considered one of the reasonable choices for the large-scale computational mechanics without the troublesome integration. In this paper, we propose a new sub-domain meshless method. It is noted that, since the method can employ both the conforming and the nonconforming sub-domains, the integration for the weak form is necessarily accurate and easy by selecting the nonconforming sub-domains with simple configuration. The linear elastic cantilever beam problem is analyzed by using the proposed method. The numerical solutions are compared with the exact solutions and the solutions of the collocation method, showing that the relative errors by using the proposed method are smaller than those by using the collocation method and that the proposed method possesses a good convergence.

In the meshless techniques, complicated non-polynomial interpolation functions are often used, which renders the integration of the weak form rather difficult. Then, an accurate and easy integration technique is desired for the meshless methods of the weak form. In this paper, a nonlinear problem is solved by using the sub-domain meshless method (SDMM), which is proposed by some authors of this paper. It is noted that, since the proposed method can employ both the conforming and the nonconforming sub-domains, the integration for the weak form is necessarily accurate and easy by selecting the nonconforming sub-domains with simple configuration. The numerical solution is compared with the exact solution and the solution of the collocation method, showing that the relative errors by using the proposed method are smaller than those by using the collocation method and that the proposed method possesses a good convergence. The numerical example shows that the proposed method possesses excellent accuracy and convergence for both the unknown variables and their derivatives for the nonlinear problem.

This paper deals with non-linear relaxation and numerical stability of friction of a rotating chain system. A method of proxy is introduced to simulate the friction in Chain-CVT (continuously variable transmission) system which offers a continuum of gear ratios between desired limits. Chain-CVT systems fall into the category of friction-limited drives as their dynamic performance and torque capacity rely significantly on the friction characteristics of the contact patch between the chain and the pulley. In this research, a planer multibody model is used to predict production chain-CVT's characteristics and examine the three friction models. The chain is modeled link by link. CVT's non-smooth dry friction is approximated by an application of proxy based ODEs and it shows drastic effectiveness of numerical stability and superiority to application of smooth nonlinear function. The model is simulated under the conditions of a constant primary pulley speed and varying secondary torque.

In this study, Fatigue Strength of Hot Work Tool Steel SKD61 was investigated. Development of new-style hot work tool steel of SKD61 is advanced at present. Data about the fatigue strength which changed the training ratio of hot work tool steel are poor. A static bending test and fatigue test were curried out an examination sequentially to make fatigue strength clear and investigated it for the observation of the fracture surface using SEM and EDX. In the case of a training ratio change, it was found that static bending strength of K materials was same as that of reference materials. K materials had lower fatigue strength than reference materials over a range of number of cycles from 10⁴ to 10⁷. As a result of fracture observation, the fracture origin was aluminum and oxygen mainly. Because alumina (Al₂O₃) to use at the time of deoxidation as a probable cause remains behind, it becomes the destruction fracture origin.

In this study, the investigation and discussion of the fracture toughness and fatigue strength of cold work tool steel were carried out. The materials under test were rotary bending fatigue specimens of SKD11, and fracture toughness specimens made that specimens. Fatigue strength, fracture toughness and hardness were measured by the rotary bending fatigue test, fracture toughness test of SEPB method and hardness test. From the results of rotary bending fatigue test, the variations were observed in the fatigue strength. From the results of fracture toughness test and hardness test, if the variation of the S-N property is small, fracture toughness and hardness were almost the same values.

In the recent oil-well development, application of drilling casing technique has been increasing. Therefore, threaded joint connecting pipes might suffer from fretting fatigue failure. In fact, in the full-scale fatigue test of the threaded joint, fretting fatigue failure occurred at the contact surface between thread crest and thread root. The fretting fatigue failure occurred at the middle of the contact surface. To clarify the mechanism, a fretting fatigue test was conducted using a bar specimen and bridge pads. As the result, the main crack formed at the middle of the contact surface similar to the real threaded joint when the contact pressure was low. On the other hand, when the contact pressure was high, the failure occurred at the contact edge. There was no stick region within the contact area. However, there was a boundary which was produced by the difference of the amount of wear. The fretting wear extensively occurred near the contact edge, but it mildly occurred at the middle of the contact area. The fretting fatigue crack was formed at the boundary between these areas.

In order to investigate near threshold crack growth behavior without oxide-induced crack closure, ΔK decreasing tests under the stress ratio 0.1 and the loading frequency 20 Hz, 10 Hz, 5 Hz and 3 Hz conditions were carried out, respectively. In case of Cr-Mo steel, oxide films were observed at the near threshold macroscopic fracture surface at 20 Hz and 10 Hz, but not observed at 5 Hz and 3 Hz. The EDX analysis on the microscopic fracture surface at either 5 Hz or 3 Hz showed that no oxide was detected in the threshold area. It is noted that the ΔK_th values were 7.0 MPa √m at 20 Hz, 5.0 MPa√m at 10 Hz, 4.6 MPa√m at 5 Hz and 3 Hz, respectively. In the range of 20 Hz to 5 Hz, the threshold showed a tendency to decrease with the loading frequency due to the decrease of the oxide-induced crack closure. On the other hand, the values became constant with the frequency smaller than 5 Hz, because there were no oxides in this range. In case of low carbon steel and cast iron, similarly to Cr-Mo steel, no clear oxides were observed in the macroscopic fracture surface tested under 5 Hz condition. It is concluded from the above results that the oxide-induced crack closure would disappear under a low frequency condition.

Mode I and mode II fatigue crack growth behavior of adhesive joints of aluminum alloys was investigated in terms of fracture mechanics and fracture surface aspect. In mode I and mode II crack growth testings, DCB specimens and ENF specimens were used respectively. In both of mode I and mode II fatigue crack growth testings, the crack growth resistance was improved by anodizing treatment of adherend. Fracture surface morphology was able to be classified into three types, that is, interfacial fracture, near-interface fracture and cohesive fracture. In the fractured adhesive, the thin surface layers with fracture aspect different from the inside region were observed in SEM observations. In near-interface fracture, crack grew along the boundary of this layer. On the fracture surface of specimens with anodizing treatment, cohesive crack propagation was dominant, regardless of mode. This is the reason for improved crack growth resistance in anodizing specimens.

In order to investigate very high cycle fatigue property of ADC12 die-casting aluminum alloy, axial loading fatigue tests were performed. Because it was known that the fatigue property of die-casting aluminum alloy was affected by the influence of casting defects inside the material, the defect inspection of the specimen was conducted by computed tomography with the industrial X-ray CT scanner after making them. At first, the fatigue test was carried out using the specimen that does not contain large casting defect. Fatigue crack initiation site was a small casting defect which could not observed by X-ray CT. It was shown that the minimum value of stress intensity factor of the crack initiation site was about 1MPa√m. After that, the fatigue test was carried out using the specimen that contain a large casting defect at lower stress condition than the fatigue strength at 10⁸ cycles and at higher stress intensity factor condition than the minimum value of that. A fish-eye pattern which was centered on the casting defect was observed on the fracture surface. The effect of casting defect on fatigue crack initiation property revealed quantitatively with stress intensity factor.

In this study, the rotary bending fatigue test and axial force fatigue test were carried out for the cast aluminum alloy. As the results of fatigue tests, the fatigue strength at N=1.0×10⁷ cycles for axial force fatigue test decreased 18% in comparison with fatigue strength of the rotary bending fatigue test. The crack initiation origins of two type fatigue tests were cast detects at the specimen surface or the specimen sub surface. In addition, in order to investigate the effect of variable amplitude loading on fatigue strength, two-step load variation fatigue test and repeated two-step load variation fatigue test were carried out. As the result of the fatigue tests under two-step load variation, in the case of second low stress σ₂=170MPa, it is thought that the fatigue cracks were initiated in the first stress damage value D₁=0.0625~0.125. As the result of the fatigue test under repeated two-step load variation, the cumulative damage value D for all specimens were more than 1.

Small fatigue crack propagation tests were conducted on Ti-6Al-4V in ultrahigh vacuum, air, and argon to fully examine the effects of vacuum on small crack growth processes. It was found that the crack propagation rate was significantly lower in vacuum than in air. The crack propagation rate in argon matched well that in air in the small crack regime; however, it agreed with that in vacuum in the long crack regime. Additionally, the fracture surface appearance in argon was quite similar to that in air in the small crack regime; on the other hand, the similarity in the fracture surface was found between vacuum and argon in the long crack regime. These tendencies in the fracture surface are coincident with those found in the crack propagation rate. Therefore, the different trends in the crack propagation rate in argon depending on the crack length obviously reflect the different crack growth behaviors. These results allowed us to conclude that the existence of gases has dominant effects on the small crack propagation, even if they are chemically inert.

In Ti-6Al-4V, fatigue fractures originate from the inside of the material in the very high cycle region (number of cycles to failure > 10⁷) at stresses lower than usual. Because of the difficulties in direct and non-destructive observation of internal cracks, the initiation and propagation mechanisms of internal cracks have not yet been clarified. Recently, μCT imaging using high brightness synchrotron radiation have been provided by the third-generation synchrotron radiation facility such as SPring-8. The very high brightness synchrotron radiation allows for a high spatial resolution of several μm or less. Thus, the present work used μCT imaging and conducted non-destructive observations on material structures which are expected to have a dominant effect on the behavior of internal fatigue cracks. As a result, it was confirmed that α phase and β phase of Ti-6Al-4V can be clearly distinguished using μCT imaging by comparing with the grain structure image observed by scanning electron microscope.