A CTOA resistance curve for mild steel was used to predict rapid crack propagation in a rupturing, subscale and full scale pressurized pipes. A CTOA resistance curve, which has a steady state value of 6°, for 0.8-mm thick 2024-T3 aluminum was also used to propagate cracks in elastic-plastic finite element (FE) models of the fracture specimens and specimens with simulated multiple site damage (MSD). The CTOA of curved crack growth in this thin 2024-T3 scattered between 4° to 8° but the resultant CTOD, which is the vector sum of the mode-I COD and the mode-II crack sliding displacement (CSD), remained a constant 0.16 mm. The CTOA of a rapidly propagating crack in 1.6-mm thick, 7075-T6 SEN specimens increased from 4.5° at a low crack velocity to a constant 7° at a higher and the terminal crack velocity.

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A finite element program was developed for the stress analysis and the identification of the mechanical properties in biological soft tissues with a mathematical formulation and a computer implementation of the incompressible transversely-isotropic hyperelastic material. The comparison between the FEM solution and the exact one in a uniaxial compression test showed that they agreed with a sufficiently high accuracy.

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A human intervertebral disc is composed of nucleus pulposus of a gel-liked material and annulus fibrosus of an anisotropic fiber reinforced material, which shows nonlinear visoelasotic behavior. In order to simulate the time-dependent behavior, this paper presents a finite element analysis using the biphasic theory proposed by Mow V.C et al. Nucleus pulposus is modeled as biphasic material composed of a solid matrix phase and an interstitial fluid phase. The intrinsic mechanical properties of each phase as well as the mechanical interaction between these two phase afford the tissue its interesting rheological behavior. The solid matrix is intrinsically incompressible, linearly elastic and nondissipative while the interstitial fluid is intrinsically incompressible and nondissipative. Further, it was assumed that the only dissipation comes from the frictional drag of relative motion between the phase. Therefore, the creep behavior under constant loading and the stress relaxation behavior under constant deformation could be simulated using this model.

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A biodegradable plastic is expected to employ as a biomaterial (e.g. re-operation needless artificial bone). In this study, the composite was made of the oriented molecular fiber and the injection molding resin, poly lactic acid (PLA), which are well known as a biodegradable plastic. The stress-strain behavior of the PLA-composite strongly depended on the molding temperature. For the PLA-composite, which was produced under a suitable molding temperature, increases of rigidity and strength. The molecular weight and strength of PLA resin were decreased due to biodegradable reaction in two months. In order to improve an interfacial adhesion, the producing of the rugged shape on a fiber surface was tried.

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Internal spinal fixation devices are commonly used for stabilizing spines with degenerative, traumatic, or tumorous disorder. However screw pullout is a possibility, especially if low density osteoporotic bone is encounterd. The final goal of this study is to propose optimum configuration of a screw for spinal fixation. Pullout tests were carried out using three types of polyurethane foam with different values of density and compressive strength. Pullout strength was changed depending on density and compressive strength of polyurethane foam. The effect of pre-bending moment on pullout strength was also discussed.

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The estimation of power in Karate-doh is discussed by means of Tameshi-wari for concrete beams. In order to examine the impact forces produced by Karate-doh hand techniques such as Syutoh-uchi and Tettsui-uchi, Tameshi-wari was performed for simply supported concrete beams and also the concrete beams suspended in air. The numerical simulation was also carried using FEM code to understand a mechanism of the impact breaking of the concrete beam by Karate-doh hand techniques. The three modes of bending deformation of the beam was verified to become dominant when it was subjected to the impact by the hand techniques. It is also found that the impact force generated between the hand and the concrete beam is estimated to be beyond 3 kN.

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A formulation is presented to evaluate the critical length of an elastic long column that buckles due to its own-weight. The column is modeled as a serial assembly of rigid links and virtual springs that stand for the flexural rigidity of the column. The critical length is searched by the dynamic criterion as the one that makes the lowest natural frequency equal to zero, which is derived by the condition that the sum of the kinetic energy, strain energy and gravitational energy of the column vibration is kept constant. The numerical examples of an aluminum column demonstrates the validity of the present formulation.

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This paper deals with stress concentration problems of a hollow circular thick walled elastic cylinder with a semicircular groove under internal pressures. A method of solution is presented for the problem by applying Green's functions for axisymmetric body force problems of a thick elastic plate. The Green's functions are defined as solutions for a thick elastic plate subjected to axisymmetric body forces acting along a circle in the interior of the plate. Stress concentrations at the groove are investigated by numerical calculations.

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An analysis of page-turning rubber roller used in ATM is conducted by FEM in this paper. The contact problem of papers and rollers are much affected by the rubber roller shape. Some parts of the roller may separate from the paper in contact. The relations between roller shapes and torques are obtained in the analysis. An unstable torque occurs for a certain type of roller shape.

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An attempt for an efficient method to select a time step for velocity Verlet algorithm, popular for molecular dynamics (MD) analysis, is presented. The idea of the method is based on the analogy between the MD analysis and the digital random vibration analysis, on the standpoint that atoms are in resonance at the lattice frequency. The proposed method showed to be about 4 times efficient compared with the empirical method for the cases of canonical ensemble of Fe and Cu.

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The paper presents analytic solution for the stresses in an elastic strip containing a sliding elliptic inclusion under uniaxial tension. The interface between the inclusion and the matrix is assumed to allow sliding or perfect bonding. The solution is obtained by using Papcovich-Neuber displacement potentials. Numerical examples are shown.

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In order to evaluate the strength of the CFRP truss pipes which support space telescope, an efficient NASTRAN finite element analysis model (FEM) was developed. By limiting detailed modeling to specific regions of interest, it was possible to verify the integrity of the structure under complex constraint and loading conditions. Requirements for the pipes are extremely low thermal deformation of less than 0.1 ppm/K, lightness, and extremely high axial strength. We measured CTE, strain, and axial strength. Comparing FEM analysis result with test result, we could make it possible to use CFRP truss pipes for the structure of space telescope.

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The inverse method applied successfully to several basic structures was extended to estimation of impact stress intensity for point bend specimens. The response functions of the specimens were estimated by de-convolving the specimen response measured near the crack tip with the measured impact force. Two methods for deconvolution were used, e.g., a simple statistical method and a CG-FFT iteration method. The ill-posed nature of the deconvolution was removed successfully by the CG-FFT method and then the excellent estimation was obtained.

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In order to clarify the effect of the size of sphere and the thickness of specimen on the surface damage and residual strength, Al_2O_3 sphere impact tests and indentation tests were carried out for Al_2O_3+TiC specimen. The diameter of sphere was 1.5mm, and thicknesses of the specimen were 2.0mm, 3.6mm and 9.0mm. The residual strengths were measured by flexural test after impact tests or indentation tests. As a result, it was seen that the residual strength decreased with the increase in impact speed. Also, the residual strengths of indentation test were somewhat smaller than those of impact test. Therefore, the possibility was shown that the residual strength due to impact test would be evaluated using the method based on the elastic indentation theory.

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When being subjected to high speed-low density particle impact such as a raindrop impact against the FRP aircraft in flight, FRP may be damaged. To evaluate the integrity of the structures, the damage mechanism caused by such impact must be clarified. GFRP disks of 100 mm in diameter were exposed to repeated impact of nylon balls in the experiments. Observation of the disk specimens during and after the experiments revealed that a white zone caused by nylon ball collision spread through the disk thickness. Sectioning of the disk specimen enables to observe the de-lamination between the second and the third layer. The close observation of the white zone indicated that the damage inside the zone consists of micro-cracking, and de-bonding of the fibers and the matrix To understand mechanisms of the observed damage modes, dynamic stress analysis was carried out by ANSYS FEM code. The analytical results indicated that shear stress component plays a dominant role to cause the white zone damage.

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