Cyclic strain controlled low-cycle fatigue tests were conducted on type 304 austenitic stainless steel under constant or two-step strain amplitude. The propagation behaviour of small fatigue cracks was observed with crack mouth opening behaviour. An interferometric displacement gage was used to measure the opening displacement of the surface cracks. The axial strain measured by the system was in very good agreement well with that measured by a differential transformer. The crack mouth opening displacement linearly increased with increasing crack length for small cracks. In the case of the two-step strain amplitude, the crack opening displacement was larger than that for constant strain amplitude when compared at the same crack length. The J-integral range calculated on the basis of the relationship between the stress and the crack mouth opening displacement was smaller than that obtained by the Dowling formula.

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The initiation and propagation behavior of small cracks of SUS 316 stainless steels under low-cycle fatigue loading at 700°C have been studied with a special emphasis on the role of oxidation both in the surface and subsurface. Intergranular cracking in air is due to preferential oxidation attack on the grain boundaries, while in vacuum the most frequent mode of cracking is transgranular. Also, coalescence of cracks in the surface plays an important role in the early stage of crack propagation both in air and vacuum, i. e., irrespective of the oxidation attack. Consequetly, the difference between fatigue life in air and that in vacuum could not be associated with the preferential intergranular cracking in the surface but with the relatively high rate of crack propagation in the depth direction in air compared with that in vacuum.

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This paper studies the crack propagation rate for three kinds of cast iron rotating disks. Fatigue crack propagation tests were carried out for flake, compacted vermicular and spheroidal graphitecast iron disks under repeated spin loading. The crack propagation rate of the flake graphite disk was the largest while that of the spheroidal graphite disk was the smallest. The crack propagation rate of the compacted vermicular graphite disk had the intermediate crack propagation rate between the two cast iron disks. The stress intensity factor range could not correlate the crack propagation rate for the three kinds of disks, while the J-integral range, which was calculated in finite element analyses, could correlate the crack propagation rate within a factor of five scatter band. The stress intensity factor range modified by the tensile strength of the material was also effective for correlatirlg the crack propagation rate for three kinds of cast iron.

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It is widely recognized that considerable scatter is often observed in fatigue crack growth rate data. The primary source of this scatter is material inhomogeneity which causes the variability of material's resistance against fatigue crack growth along the path of the crack, and hence the statistical properties of the distribution of crack propagation fatigue life due to random crack propagation resistance are often needed in structural reliability analysis. From this point of view, Ishikawa et al. showed a stochastic fatigue crack growth model based on a Markov approximation method, and derived the theoretical crack propagation life distribution from it. But there has been no way to estimate the one unknown parameter which appears in their solution. In this paper, a simplified method to estimate that unknown parameter is proposed. Monte-Carlo simulation is also performed to confirm the proposed method, and satisfactory results are obtained.

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This paper considers the axisymmetric problem for a transversely isotropic cylinder containing a penny-shaped crack. Expressing the stress component along the crack plane as an appropriate series, the problem is reduced to the solution of an infinite system of simultaneous equations. The displacement and stress distribution around the crack tip are shown graphically for various magnitudes of crack diameter. It is shown that the stress intensity factor is independent of the transverse isotropy of the cylinder under constant torque.

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In a previous paper, the present authors discussed the path-integral expression of the J-integral range, ΔJ, for short fatigue cracks emanating from notches, and showed that ΔJ evaluated based on the crack-opening level was an appropriate parameter for characterizing the near-tip stress and strain fields. In this study, finite-element simulations of fatigue crack growth from notches were conducted. The ΔJ-values evaluated by the path-integral were compared with those estimated by El Haddad's simple estimating formula proposed for short fatigue cracks at notches, and with those estimated by Dowling's formula and by Cho's formula proposed for deep cracks. The ΔJ evaluated by El Haddad's formula did not agree well with ΔJ values evaluated by the path-integral. On the contrary, ΔJ values evaluated by Dowling's formula based on the crack opening level agreed well with ΔJ values evaluated by the path-integral.

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In order to clarify the fatigue process of bone, rotating bending fatigue tests and creep tests were conducted using bovine femoral compact bone in laboratory air and Ringer's solution. The results obtained are summarized as follows. ( 1 ) Fatigue lives in laboratory air and Ringer's solution showed little difference. ( 2 )At high stress levels above 100 MPa, creep rupture time and fatigue failure time are nearly the same, but at low stress levels below 100 MPa, the latter is shorter than the former. This indicates that fatigue damage accumulation controls the fatigue fracture process at low stress levels. ( 3 ) During the fatigue process of bovine bone, several microcracks were initiated and propagated accompanied by crack coalescences among them. The crack path was zigzagged. ( 4 ) The relation-ship between the ratio of crack initiation cycles N_i to fatigue cycles N_f and stress amplitude was investigated. The ratio N_i/N_f decreased with a decrease of the stress amplitude region. ( 5 ) There is a linear relationship between crack growth rate da/dN and stress intensity factor ΔK on the log-log plot, and the Paris equation da/dN=CΔK^m holds, where C and m are C=5. 25×10^-9 and m=1. 49, respectively.

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Statistical analysis is necessary in evaluating the fatigue life of structures. In the present study, rotating bending fatigue tests were carried out on specimens with two small blind holes of a 5052 A1 alloy in order to investigate the distribution characteristics of the fatigue crack growth life based on the small-crack growth law dl/dN= C₁σⁿ_al. The crack growth rate in each specimen was determined uniquely by σⁿ_al, therefore the crack growth life can be predicted by the small-crack growth law. On the assumption that the value of n is a fixed one and the value of C₁ is a random variable, the distribution of the crack growth rate can be evaluated through the value of C₃ in the relationship dl/dN=C₃l. C₃ follows a Weibull distribution approximately. The calculated distribution of the ocracy growth life based on the small-crack growth law and the distribution of C₃ was in good agreement with the experimental results.

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The influence of fiber orientation and content on tensile strength and fatigue crack growth resistance in short-glass-fiber-reinforced polycarbonate was investigated. The fiber volume fractions of four materials fabricated by injection moulding were 0%, 10%, 20% and 30%, and short fibers in these materials were aligned mostly in the mould-fill direction. Young's modulus and tensile strength parallel to the fiber direction were higher than those perpendicular to the fiber direction, and they increased with an increase in the fiber volume fraction. In the da/dN - ΔK_l relation, resistance to fatigue crack growth was influenced by the fiber orientation and content. The resistance in L-orientation was higher than that in T-orientation, where L-and T-orientations denote crack growth perpendicular and parallel to the fibers, respectively. The resistance increased with an increase in volume fraction for L-orientation, but it was not in order of volume fraction for T-orientation. When da/dN was plotted against the stress intensity factor normalized by Young's modulus, all the data lay within the narrow band.

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was proposed based on the body force method. In the present method, the newly introduced basic density function of the body force doublet make it possible to exactly express the mathematical stress fields near the interface crack. As the overlapping area of the crack is very small compared with the crack size, this phenomenon is usually neglected in ordinary numerical methods, and the stress intensity factors are calculated indirectly by using an extrapolation method with displacements or stresses near a crack tip. However, in the present analysis, the stress intensity factor of an interface crack can be obtained directly from the value of the weighting function at the crack tip.

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Fracture tests of aluminum/epoxy dissimilar materials with an interface crack are carried out under various mixed mode conditions which can be realized easily by using circular disk type (brazil-nut-sandwich) specimens and changing the direction of compression or tension loadings. In the brazil-nut-sandwich compression tests, the crack kinks into the epoxy resin and the fracture angles are well predicted by the σ_θmax criterion proposed by the authors. In the brazil-nut-sandwich tension tests, the fracture occurs along the interface and the mixed mode fracture criterion are clarified experimentally. A method to evaluate the possible path and the strength of the interface crack is discussed by comparison of both criteria.

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To study a fatigue life prediction method for press-formed corners in thin steel sheet structures, bending fatigue tests were made on press-formed members. The hardness of the press-formed corner on the member, where a fatigue crack would appear, was measured. The results showed that the hardness is greater than that of a steel sheet as received. On the other hand, the strains on the inner and outer surfaces of the press-formed corner were analyzed by FEM and experiments. The results showed that the press-formed corner is under the combined load of an axial force and a bending moment. To simulate the hardness of the press-formed corner, a smooth specimen was prestrained and the fatigue tests of prestrained specimens were performed under the same combined load condition as the press-formed corner. It was confirmed that the Δε-Nf diagram of the prestrained specimens makes an accurate fatigue life prediction of the press-formed corner on members.

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In this study, instrumented Charpy impact tests are carried out with ordinary thickness ductile cast irons containing various amounts of pearlite in order to examine the effect of matrix structure on the dynamic fracture toughness and crack growth behavior. CTOD is smaller and crack growth occurs more easily with increasing pearlite content in the matrix. The relationships between J(ΔC)and J(R) vary with pearlite content. For ferritic and ferritic-pearlitic materials, J(ΔC) is nearly equal to J(R) and these points are located near the Δa=0. 1mm point. For fully pearlitic material, however, J(ΔC) locates near the Δa = 0. 4mm point and overestimates the fracture toughness, while J(R) underestimates it from the view point of applied load. It is considered therefore that J(mid) is a reasonable measure for the fracture toughness of ductile cast irons, irrespective of the pearlite content in the matrix.

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Life prediction methods of creep fatigue were investigated to consider applications to Hastily XRs at very high temperatures where materials would be damaged severely by creep deformation. The ductility exhaustion rule, coupled with a creep constitutive equation consisting of primary and secondary stages, showed a good prediction of creep-fatigue life as well as the damage-rate equations. The strain range partitioning method was also discussed regarding its possibility for life prediction. The results of these methods were compared with the time fraction rule in conjunction with the Miner's rule. In these experiments, creep tests were done under constant stress condition in air, and low. cycle fatigue tests were carried out with and without a dwell period in vacuum. Creep-fatigue damage was evaluated in the life of low-cycle fatigue tests with a dwell period. All specimens were fabricated from the same hot-rolled plates to reduce scatter in different heat treatments.

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Following the creep-fatigue tests with Modified 9Cr-1Mo steel in a high-vacuum environment, creep-fatigue fracture surfaces were investigated by SEM. In the cases where the creep-fatigue life is time-or rate-independent, the fracture mode is the transgranular type, but some differences were observed in the number of dimples, which depends on the strain wave form. When time-or rate-dependent life reduction takes place, the primary fracture mode is found to be of the intergranular type which is observed on the inner side of the specimen, but becomes transgranular on the outer side. The area fractured in the intergranular manner is correlated to the time-dependent damage variable calculated by the creep-fatigue life evaluation model based on the overstress.

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Creep tests of a continuous fiber-reinforced metal matrix composite SiC_CVD/Ti-15-3, which is one of the advanced metal matrix composites, are performed for three fiber directions 0°, 45°and 90° at 450°C. Specimens are chucked inside a furnace to realize a uniform temperature field in the gage section, and elongation in creep is measured. We find the following : ( 1 ) Creep deformation and rupture can occur even in longitudinal creep at a stress level much lower than the tensile strength, although the SiC_CVD fiber itself does not creep at all. ( 2 ) This creep behavior is explained partly if we consider the stress relaxation in the matrix material during longitudinal creep tests of the composite. ( 3 ) Off-axis creep of 45°has some ductility, which is greater under lower stress.

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MA956 and MA957 of oxide dispersion strengthened (ODS) steels are expected as future nuclear fusion material because of their superior mechanical properties and resistance to irradiation at high temperatures. However it was found that a cavity was formed upon heating to higher temperatures. After the materials were maintained for a long time at temperatures from 1 073 K to 1 473 K, the cavity formation and growth process were observed and analyzed. The shape of the cavity was spherical in MA956 and disk-like in MA957. The cavity volume fraction increased with the holding temperature and time. The reason for cavity formation and growth is that precipitates of Al₂O₃ and TiO₂ become the nuclei in MA956 and MA957 respectively, and vacancies and Ar gas atoms are accumulated at the interface of the precipitates and matrix. For the growth rate of the cavity, good agreement between the experimental and theoretical values, considering the contribution of gas atoms, was obtained.

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The destructive phenomenon of brittle and fatigue fracture is becoming extremely important in the problem of structures' safety. In this paper, to elucidate the fracture mechanism, it is tested experimentally to explicate the destructive phenomenon of the fractured section and fissure progression occurring due to thermal shock in typical brittle glass materials. Specifically, by the application of the newly developed method of applying electric resistance-vacuum evaporated thin films, it became possible to accurately measure the velocity of fissure propagation and also each block of glass and ceramics. As a result, the maximum velocity of fissure propagation for the glass was approximately 1 500-1 700 m/s and its average velocity was 650 m/s. It is also found that the velocity of fissure propagation in the glass by thermal shock under the condition of adding load by four-points bending is almost approximatrely 3 000 m/s.

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Two-dimensional stress waves in a transverse isotropic cylinder are analyzed numerically, when an axisyrnmetric impulsive load is applied to the end surface. For the numerical analysis of the dynamic behavior of the transverse isotropy, the extended finite difference method based on integration along bicharacteristics is proposed. For stainless steel-aluminum Composites, the effect of the transverse isotropy on the propagation of stress waves is demonstrated.

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The strength retained after thermal shock was analysed theoretically and the probability of crack occurrence of ceramics was predicted using the Weibull statistical theory of fracture. For the purpose of verification of this proposed analysis, thermal shock tests on three kinds of ceramics using water as the quenching medium were performed. As a result, analytical results were found to be in good agreement with results of thermal shock tests. Furthermore, the critical quenching temperature difference was defined as the mean value of crack occurrence quenching temperature differences. Consequently, these proposed analytical results were also in good agreement with results of critical quenching temperature differences obtained by thermal shock tests, performed by quenching in water and liquid sodium.

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The strength of adhesive joints of laminated thin sheet metals under tensile loading was investigated both analytically and experimentally. Aluminum alloy, brass and carbon steel were used for the adherends and epoxy resin for the adhesive. The stress and strain distributions of the joints were analyzed by the elastic finite element method on the assumption of a plane strain state. Their validity was confirmed by the experiments. The initial failure strength of the joints was evaluated by applying each strength criterion to the adherends, adhesive and their interfaces respectively. The stress redistributions after initial cracking were computed to predict the final fracture strength of the joints. The final fracture strength increased according to Young's modulus that of the inner lamina material became higher and that of the outer lamina material became lower.

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To estimate the truncation strength of silicon nitride after proof testing, the crack growth behavior was studied using a semi-circular surface crack induced by a Knoop indenter. Assuming that the relation between the arack growth velocity, V, and the stress intensity factor, K, is merely composed of two regions (Region I and Region II), the transition stress intensity factor value from Region I to Region II, K was predicted from the crack propagation parameter, A, n, and the fracture toughness, K_IC. Using the relation between V and K obtained, the truncation strength of silicon nitride proof-tested at room temperature was entimated. Further more, the fast fracture strength and the static fatigue life were measured at elevated temperature, and the effectiveness of proof testing was investigated.

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CT and CCT specimens with or without side grooves are analyzed elastic-plastically by the 3-dimensional finite-element method. The J-integral evaluations are carried out on a great many specimens of various thicknesses. The J value obtained by a simple equation using load-displacement data becomes lower than the analytical J value at the center of a specimen with decreasing thickness. The former is 15-20% lower than the latter for thin specimens. However, it is possible to estimate the valid J value at the center of a specimen by the simple equation using β√(B×Bn)(β depends on thickness) as an effective thickness. The simple equation for a CT specimen of ASTM standards underestimates the J value for the non-side-grooved specimen and overestimates it for the side-grooved specimen.

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Demand for corrugated flberboard for use in multi purpose packing materials has grown recently, and the requirements for mechanical precision and strength are becoming more stringent. Because corrugated fiberboard is composed of a top liner, a bottom one and a wavy-shaped medium liner, the warping deformation depends on the difference in the fiber orientation and the expansivity between top and bottom liners. To prevent the warping deformation of corrugated fiberboards, it is necessary to formularize the warping deformation and elucidate the mechanism of warping. In this study, a prediction equation of warping deformation for corrugated fiberboards is derived from the lamination theory, and the mechanism of the warping deformations is investigated. The relationship between the warping and the parameters influencing the warping has been elucidated by a simple prediction equation, and prediction of the warping deformation is made possible. Twisting warping is closely connected with the difference in the fiber orientation angle between the top liner and bottom liner, and increases with fiber orientation angle. The bending warping and twisting warping increase with the anisotropy ratio of Young's modulus and the anisotropy ratio of the expansivity, and the increased ratio of bending warping in the machine direction (MD) is larger than that in the cross direction (CD).

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In this paper, the plane strain problem for three-phase materials formed from three isotropic homogeneous wedges with arbitrary angles is presented. In particular, the eigenequation for the three-phase bonded structure was analytically derived in order to investigate the order of the singularity in the stress field near the apex. At this time, four Dundurs composite parameters, α₁₂, β₁₂for material 1-2 and α₂₃, β_, <23> for material 2-3, composed of three pairs of shear modulus and Poisson's ratios were used. In the case where the half-plane consists of apex angles of π/6, π/3 and π/2, the order of singularity in the stress field for different bonded order and that for different material combinations are studied in detail.

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The recovery stress under constant residual strain associated with the R-phase transformation in TiNi shape memory alloy was investigated. The results can be summarized as follows. The larger the residual strain, the larger the recovery stress was. The behaviour of the recovery stress which increased along the reverse transformation line on the stress-temperature plane depended on the volume fraction of the R-phase. The recovery stress was described well by the constitutive equation considering the volume fraction of the R-phase. The higher the shape memory processing temperature, the larger the rate of decrease in the volume fraction with an increase in the test temperature was.

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In the top end closure of cylindrical storage tanks for refrigerated liquefied natural gases (LNG)subjected to internal pressure, one failure mode is bifurcation buckling. The top end closure is torispherical, and buckling may occur elastic-plastically. This paper describes the buckling characteristic and the buckling pressure of a top end closure of LNG tanks, which is designed according to the current design code, API Standard 620. The axisymmetric shell finite-element method considering both geometrical and material nonlinearity in the prebuckling state is carried out. Results show that the current design code estimates the buckling pressure fairly conservatively.

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'Kinking' is known as an unstable behavior of a twisted slender rod, which occurs after the torsional buckling. It is simulated by a hyper-elastic finite element code developed by the authors, with hexahedral solid elements. The mechanical characteristics and the criterion of the kinking are successfully discussed. An incompressible constraint to model a rubber-like material is introduced in the simulation by the Lagrange multiplier method and the penalty method. It is found that the former method is computationally more efficient in the case of extremely large deformation such as kinking.

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Simultaneous pairs of dual integral equations with trigonometric kernels encountered in the analysis of mixed boundary value problems by Fourier transforms are solved by reduction to a coupled system of singular integral equations. The method of reduction indicated here is based on the relationship between the Fourier transform and the Hilbert transform. The numerical solution of the simultaneous singular integral equations is obtained by using two types of integration formulae. The accuracy and the convergency of the results are examined by examples of crack problems.

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This paper presents a method to detemine the distribution of the Younng's modulus of function-ally gradient materials by bending testing. In the method, the measured values of the flexural rigidity, which are obtained by reducing the height of the specimen, are used to inversely analyze the distribution of the modulus across the thickness. The solution is obtained through minimizing the residual between measured data and estimated values. The Davidon-Fletcher-Powell method is employed for minimization of the error. The practical applicability of the method is examined through several examples.

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The dynamic buckling of a reactor containment vessel under earthquake load is simulated using the nonlinear finite element method to assess the safety margin of the conventional design. The nonlinear FEM is based on the Mixed Interpolated Tensorial Components shell element proposed by Bathe and elaborated by the authors for sensitivity analysis in transient problems. It is found that the buckling load estimated by the conventional static analysis method is smaller (about five-eighths)than that given by the present dynamic analysis method. Sensitivity of the system parameters such as initial imperfection is also studied, leading to implications for design and quality assurance. The effects of the orientation of the polar crane and the existence of hatches on the dynamic response are also studied.

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For analyzing on electromagnetic field in 2 or 3 dimensions, a finite-element methd and a boundary element method are widely used. However, there remain some prblems, especially concerning CPU time and memory space in 3 dimensions. A third method which utilizes the advantages of both methods was proposed as a "combination method" and is mainly applied to open field problems. In this paper, a study of magnetic shield analyses by the combination method is presented. It is shown that in closed field problems the CPU time and the memory space are reduced effectively using this method.

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If initial temperature is assumed to be constant, the boundary element method (BEM) does not need a domain integral in unsteady thermoelastic problems without heat generation. However, under heat generation or nonuniform initial temperature distribution, the domain integral is necessary. This paper shows that the problem of unsteady thermoelasticity under nonuniform heat generation and with nonuniform initial temperature distribution over the region can easily be solved without a domain integral by means of the boundary element method. This method can also be applied to unsteady thermal stress problems under general complicated heat generation. However, for general heat generation the domain must be divided into small domains, where distributions of heat generation satisfy the Laplace equation.

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In conventional theory, it is assumed that continuum state can be determined instantaneously. This assumption restricts the arguments for quantities of state and constitutive equations. In a previous paper, noninstantaneities were introduced in the laws of thermodynamics, to express the constitutive equation of stress including the effect of viscoelastisity. In this paper, we discuss that nonequilibrium processes can be expressed by means of this concept of noninstantaneities in continuum mechanics. The 1st and 2nd laws of thermodynamics are expressed considering the effect of the nonistantaneities of thermodynamic quantities. Then a balance law for the newly defined entropy flux in this paper, is formulated to make the balance equation system complete. Furthermore, the Clausius -Duhem inequality that characterizes materials with the noninstantaneous state is derived. On the basis of the Clausius-Duhem inequality, it is suggested that the constitutive equation of stress restricted thermodynamically, depends on the time rate of the temperature for the nonequilibrium processes.

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In this paper, the thermodynamic behavior of materials for nonequilibrium processes is discussed in continuum mechanics. The hypothesis of local equilibrium is assumed in a point of continua in conventional theory. In the previous paper, to avoid the above hypothesis, gradients of the thermodynamic quantities were introduced in the entropy inequality on the basis of the concept of thermopolar materials, to construct the basic theory. In the present paper, the average value and fluctuations of thermodynamic quantities are strictly defined. Therefore, Clausius-Duhem inequality and balance equations for fluctuations are newly derived considering the balance laws of microscopic energy moment for not only the 1st order, but also the 2nd order. Moreover, the arguments of response functions for internal forces and new dissipative fluxes are determined. As a result, it is suggested that the constitutive equations and heat conduction also depend on the microscopic curvature of the temperature for nonequilibrium processes.

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Fracture behaviors of brittle polycrystalline solids such as ceramic materials are deeply related to microcracking. Continuum damage mechanics is considered a powerful theoretical framework to deal with brittle microcracking materials, however, it is fairly difficult to obtain analytically as well as experimentally evolution equations for microcracking and reduced elastic compliances of microcracked solids. In the present study, a mesoscopic (grain level) simulation method using a discontiuum mechanics model is proposed to solve these problems. The validity and limitations of the isotropic theory of continuum damage mechanics are studied in the first report.

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The mesoscopic simulation method proposed in the first report of the present study has been applied to the analysis of a brittle polycrystalline solid under proportional loading of biaxial stresses. The validity and limitations of the anisotropic theory of continuum damage mechanics using a second order tensor as damage variables have been studied through comparisons of simulational results and theoretical predictions. It has been shown that the existing anisotropic theory is inapplicable to the compression-predominant stress state because of an associated type of damage evolution equation, although it is effective in the tensile stress field.

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The atomic-scale changes of a structure around the crack tip in a fcc crystal under anti-plane shear loading are analyzed by molecular dynamics (MD) simulation. The interatomic force interaction is assumed to be derived from the many-body potential proposed by Finnis and Sinclair. The crack surface and its front are assigned to ( 1 ) [110] (001), ( 2 ) [110] (111), and ( 3 ) [110] (110). The fixed boundary condition is adopted, that is, the displacement of the atoms located at the boundary is given, so that the atomic block is embedded in the elastic singular field with the prescribed stress intensity factor K_III. Ductile deformation with the emissions of screw dislocations from the crack tip is observed in every case. The dislocation moves in the {111} slip plane and dissociates into two Shockley partial dislocations. Repulsion between disocations prevents their movement, and so-called cross slip appears ; that is, some dislocations change their slip plane. Good correspondence is shown between the MD simulation and the results obtained from a continuum model of the crystalline material given by Rice et al.

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With the molecular dynamics method, the molecular aspects of deformation are studied numerically to relate the molecular or lattice particle motion to the stress-strain characteristics. The forces acting on the particles are assumed by the Lennard-Jones potential for the purpose of obtaining the qualitative features of solid deformation. The effects of the temperature and lattice defect on the solid deformation are also investigated. The local stress has a predominant effect on the solid failure, with the maximum value independent of the temperature and the lattice defects.

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It is clinically proven that certain screws cannot be well fixed with an internal fixation plate in a tibial fracture. This paper investigates the mechanical properties of fixation of the fractured ends of a tibia fixed with the internal fixation plate. For the purpose deformations of tibia are measured by holographic interferometry in various conditions. The specimens are 1) dried normal tibias, 2)dried fractured tibias fixed with a fixation plate and 3) dried fractured tibias fixed with a fixation plate but with two of the screws removed. The results showed that a greater concentration of fringes in the distal fractured part was observed in specimen 3 than in specimen 2. This indicates that the ability to fix tibial fragments with the plate was weaker in specimen 3 than in specimen 2. The same measurements were carried out for a fresh bone. The deformations for the fresh bone and the dried bones were very similar.

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This paper describes an application of a mutual combination-type neural network to the optimum design problems of truss structures. The optimum design problems of truss structures are changed to some combinatorial optimization problems. The Hopfield model and the quadratic energy function are used to solve the design problems. The method is able to obtain feasible solutions for several optimum design problems. The effectiveness of this method is demonstrated by two examples of the minimum weight and maximum stiffness design problems of truss structures.

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