Structural metallic materials usually have various types of defects such as inclusions, grain boundaries and mechanical notches. These defects shorten the fatigue life of the material. In this study, the fatigue life distribution of a specimen having many defects was derived from the original fatigue life distribution of a specimen having only one defect by applying a concept of the extremes distribution. The qualitative trend of the experimental results was well explained by this analytical model, but the quantitative effect of the number of defects was not successfully evaluated. In order to overcome this difficulty, the effective factor ξ of the defect number was introduced into the formulation of the fatigue life distribution of the specimen having any number of defects. Analytical results thus obtained were in good agreement with the experimental results of fatigue life distribution characteristics.

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The corrosion fatigue crack initiation mechanism of 17-4PH stainless steel was investigated in 100 ppm NaCl solution at 130°C. The corrosion current variation caused by cyclic stressing was measured in a simulated electrochemical system. The corrosion current was detected at the stress level above the corrosion fatigue limit, wich means that the outflow of corrosion current was the trigger for the crack initiation. The outflow of corrosion current seemed to be caused by the mechanochemical reaction of the micro plastic strain generated at the edge of a micro nonmetallic inclusion. It was concluded that the critical stress required to induce the crack initiation was determined by the appearance of plastically strained metal exposed to the corrosive environment.

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Influences of recycling process on the fatigue crack growth property of PA·MXD6 were examined. The main results obtained were as follows : (1) The FCP property of recycled PA·MXD6 became worse than that of the virgin material. In particular, the decline of the fatigue property was fastest in the first recycling process. (2) From the fractography using SEM, it was understood that the detrimental effect of the recycling process on the fatigue property was caused by the breakdown of the glass fibers during the recycling process. (3) The crack tip heating in the recycled material was increased more remarkably than in the virgin marerial. This is because the crack tip opening displacement was increased more markedly than in the virgin material. Therefore, it could be interpreted that the influence of the recycling process on the FCP property was caused by enlarging the crack tip opening.

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The effects of water absorption and desorption on fracture mechanisms of two typical materials, a short carbon fiber reinforced material and a chopped strand reinforced material with nylon matrices, were examined by AE monitoring and SEM. It was found that the matrix became brittle in vacuum-dry specimens, but became ductile in the water-absorbed specimens. These gave rise to different fracture behaviors of the materials used. In the short carbon fiber reinforced material, the matrix fracture and fiber breakage were main fracture forms in the vacuum-dry specimens, while the pull-out became the main fracture form in water absorbed specimens and those subjected to general air conditions. In the chopped strand reinforced material, the cracking between chopped tapes, and debonding of fiber/matrix in a chopped tape became marked as the moisture content of specimens increased. Especially in the water absorbed specimen, the matrix became more ductile, resulting in a large decrease of the interfacial strength, then leading to easy pull-out of fiber strands and chopped tapes.

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A study has been conducted on the relationship between the initiation and propagation behavior of a fatigue crack originating at the non metallic inclusion and the fracture-mode transition from a surface to subsurface fracture known as fish eye fracture in high-strength steels. Special attention is paid to the propagation of microcracks originating at each inclusion both on the specimen surface and in the subsurface. The results obtained are summarized as follows. (1) Metallographic observation using SEM revealed that the initiation of microcracks from inclusions occur at numerous inclusions both on the specimen surface and in the subsurface. (2) The initiation of these microcracks from inclusions on the specimen surface occurs at a very early stage in the fatigue cycles. (3)The propagation of a crack initiating from an inclusion on the specimen surface stops at an early stage in the fatigue cycles before failure occurs as a fish eye fracture. (4) These phenomena suggest that there exists a fatigue limit in the surface fracture mode, and that the mechanism of fracture mode transition is associated with the difference in crack propagation behavior of microcracks from inclusions on the specimen surface and in the subsurface.

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A model for the onset of ductile fracture in porous media is proposed and applied to the onset of void coalescence in the neck of a tensile specimen. A constitutive law for a rigid-work hardening porous solid is developed, based on an anisotropic yield function introduced by the authors in a previous report. The constitutive law embodies the void evolution model suggested by Rice and Tracey. The onset of void coalescence is based on a criterion of internal necking of the matrix ligaments between the voids. This model was developed by Thomason for the plane strain case. The model is extended in the present study to include axial symmetry, and then it is shown that the extended model coincides qualitatively well with the fracture strain variation obtained experimentally by Edelson and Baldwin for sintered porous materials.

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It is known that intrinsic mechanical stresses exist in a general free surface or interface, because of surface atomic structure changes relative to the bulk. This paper presents an analysis using the interrelationships between surface stresses, free surface and volume stress deduced in the previous paper. The surface stresses have a close relationship with surface energy and surface geometry (mean curvature) of materials. In the present paper, an elastic contact problem which pressed an axisymmetric elastic body into an elastic half region coated with a thin elastic film is analyzed by using the three-dimensional theory of elasticity. In this analysis, the relevant dimensionless parameter, called the elastic capillary number, which is a function of surface energy, elastic modulus and the film thickness, is introduced. It is shown that the modulus for the thin film apparently increases and the bulk stress also increases by taking into account the surface stresses.

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In order to evaluate the mechanical properties of a very thin film, a method combining the analysis with the experiment of triangular pyramidal indentation (the nanoindentation method) is proposed. The particular formulation of FEM of triangular pyramidal indentation is established. The indentation load-displacement relationship is obtained for a thin film sputtered or sprayed on a substrate with different mechanical properties. The effects of film thickness and mechanical properties of the film and the substrate are clarified quantitatively. Coupling the analytical results with experimental measurements enables one to determine the mechanical properties of very thin films.

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Due to the recent development of computers, experiments have been replaced with computer simulations in various fields. Regarding this, the scale of the model to be solved tends to be extremely large. Notably, the power of engineering workstations (EWSs) have grown rapidly, and in order to perform large scale analyses with the EWS, the present authors have proposed the parallel use of several computers connected to a network. In other words, a computer network is regarded as a parallel computer. As a parallel numerical algorithm for the finite element analysis, the present authors have proposed a domain decomposition method combined with an iterative solver, where the entire analysis domain is divided into a number of subdomains without overlap. Using the present algorithm, the code for elastic-plastic finite element analysis is implemented on a network which is composed of several engineering workstations. Several tests are performed showing the high efficiency of the present method.

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The closed-form solution for the stress, strain and displacement fields around the elliptical cavity subjected to uniform stresses at infinity in two-dimensional anisotropic body was presented previously by us, using Lekhnitskii's and Green-Zerna's methods. Deformation and rigid body rotation on the contour or near the crack in an anisotropic medium can be expressed in terms of this exact solution. Their forms are much more complicated than those in an isotropic medium because they include many complex constants determined by anisotropic material properties. Numerical results are also obtained by using our solutions and are shown that their results coincide with the case of an isotropy or Mode I condition in anisotropy.

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A fictitious equivalent undamaged configuration B^*_t of an element of a damaged material is first introduced into a three-dimensional Riemannian manifold by excluding the irrelevant rigid rotation of the element. Then a new symmetric damage tensor for three-dimensional anisotropic damage is developed in terms of Finger's tensor of a fictitious deformation gradient from the current damaged configuration B_t to the equivalent undamaged configuration B^*_t. The damage tensor components are expressed in terms of the metric tensor components of the convective coordinate systems of B_t and B^*_t. Furthermore, the effective stress tensor of damage mechanics is defined by the equality of stress vectors acting on the damaged and equivalent undamaged plane elements, and the mechanical interpretation of the effective stress tensor and its symmetry condition are discussed. The symmetry condition is also formulated by means of a commutator tensor formed by the tensor pairs : damage tensor-Cauchy stress tensor and damage tensor-reversible gradient. Finally, the symmetrized effective stress tensor is introduced and interpreted.

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In order to develop general anisotropic plastic constitutive equations of metals, the plastic behavior of the initially anisotropic metals after multiple-prestrainings has been investigated experimentally. From experimental results, a new constitutive model which contains the new evolutional rules of an outer/bounding surface based on the two-surface concept is proposed in this report. Also, benchmark tests are performed to estimate the applicability of the new model compared with the two-surface constitutive models of isotropic/mixed hardening types.

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This paper deals with numerical solutions of singular integral equations of the body force method in interaction problems of elliptical holes and elliptical inclusions in a shear stress field. The problems are formulated as a system of singular integral equations with Cauchy-type or logarithmic-type singularities, where the densities of body forces distributed in the x-and y-directions of infinite plates having the same elastic constants of the matrix and of the inclusions are unknown functions. In order to satisfy the boundary conditions along the inclusions, eight kinds of fundamental density functions proposed in our previous paper are used ; then the body force densities are approximated by a linear combination of the fundamental density functions and polynomials. The accuracy of the present analysis is verified by comparison with the results obtained by the previous research. The present method is found to give rapidly converging numerical results for stress distribution along the boundaries of both the matrix and the inclusions.

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In this study, the deformation and the stress due to the bending of corrugated fiberboard sheet were clarified by three-dimensional large deformation elasticity-plasticity analysis using the finite-element method. Further more, the influence of material properties and process conditions on bending stress was examied and the following results were obtained : the residual stress concentration after the springback will be relaxed by the increase in young's modulus of corrugated media ; and the increase of stress σ_z, due to the bending at end of bottom liner in contacted with the rotating body, will be restrained.

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In a bolted connection, failures usually initiate at the root of the first bolt thread where the maximum stress occurs. Patterson and Kenney have conducted a comprehensive study for reducing the maximum stress using a 3-dimensional photo-elastic method, and they suggested that a modified nut with straight bevel at the bearing surface was very effective. However, they only dealt with M30 and estimations on the geometry of the modified nut had not been necessarily sufficient. Consequently, it is considered that numerical analyses are needed to determine the optimal shape of the modified nut and to accurately estimate how much the modified nut could reduce the maximum stress for various design factors. In this paper, a numerical approach for multibody contact problem with FEM is proposed by incorporating a "regularization method" into stiffness matrices to avoid the singularities involved and the validity of the modified nut is investigated as elastic contact problems using the FEM. It is concluded that modified nuts are significantly effective for bolts with large nominal diameter and fine pitch and are practically useful compared with pitch modification and tapered thread methods.

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The fundamental solutions are derived for the two-dimensional elastic fields of a point force and a dislocation acting at a point in a plane of two joined semi-infinite anisotropic plates. Lekhnitskii's complex potential approach is used, and a general expression of the solutions is obtained in a closed form. No symmetry is assumed for the elasticity of the anisotropic material in the investigated plane. Taking into consideration the case of an isotropic-anisotropic two-phase medium and the case of an isotropic-isotropic two-phase medium, solutions are given for all the possible combinations of the materials with either s₁≠s₂ or s₁=s₂, where s₁ and s₂ are the roots of the characteristic equation of the material.

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The plane elasticity problem of a point force and a dislocation acting at a point outside an elliptic inclusion in an infinite plate was solved by Stagni in 1983. However, in the present study, it is found that the solution by Stagni does not converge for the case in which the point of action of the point force and dislocation is near the interface. A solution applicable to all cases, including the case where the point force and dislocation are applied at a point on the interface, is obtained in this paper in the form of functions plus an infinite series. By carefully defining the functions, the infinite series shows a good convergence.

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Advanced fiber-reinforced composite materials have been used for structural members because of their high specific strength and stiffness. A study is conducted on the stability of symmetric cross-ply laminated cylindrical shells under static and periodic external pressure of short duration. The cylindrical shell can withstand an impulsive load greater than the static buckling pressure if the loading duration is very short compared with the free vibration period of the laminated cylindrical shell in the first mode. The inevitability of dynamically unstable behaviors and the effects of various factors, such as load ratio, number of layers, stacking sequence, fundamental natural frequency, driving amplitude of the vibration and dynamic unstable mode, are analytically clarified.

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The forming limit of sheet metal laminates under a biaxial stress condition is investigated by performing punch-forming experiments on two-ply laminate of aluminum/SUS 430, three-ply laminate of SUS 304/aluminum/SUS 430 and their component sheet metals. The data of necking-limit strains of the laminates lie between those of their component sheet metals. A criterion of localized necking for the laminates, in the negative strain-ratio condition (β=ε₂/ε₁<0), is derived based on Hill's theory of localized necking. For the case of the positive strain-ratio condition (β=ε₂/ε₁>0), the modified Marciniak-Kuczynski-type analysis, which assumes that an initial inhomogeneity in a sheet develops into localized necking, is conducted with the consideration of void growth in the groove of the sheet. The calculated forming limit diagrams show the same tendency as seen in the experimental results. The effect of prestrain generated in the roll-bonding process on the formability is discussed.

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Nickel-base superalloy IN738LC is widely used for heavy-duty gas turbine buckets. But the buckets in current advanced gas turbines are exposed to extremely high temperature, which induces significant material degradation during service. Therefore an evaluation of the resistance against damage caused by foreign objects is required to establish a material degradation assessment system. In order to investigate the damage caused by impact from a projectile, the long-time aged material at 750°C-900°C up to 24000h of IN738LC are artificially produced and the single-particle fracture test was made on a particle impact test rig. In this study, introducing the fracture model, in which the strain rate controlling process is that dislocations move past γ' precipitates by looping, the critical velocity of impact fracture is explained as a function of projectile size, target thickness, mechanical property such as material elongation and the microstructural parameter of a ratio of the second power of the γ' interparticle distance to the γ' mean diameter. Furthermore, using measured impact loads, the relationship between normalized deformation work induced by impact projectile and impact velocity is discussed.

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High-Tc superconductors (Sr_0.7, Ca_0.3)_1-xCuO₂ are synthesized under a pressure of 5.4 GPa and at several temperatures for 30 minutes. The superconducting phase is stable under high pressure. Therefore, superconducting properties are not affected by high pressure and the density almost reaches the crystallographic one. The obtained superconductors show better mechanical properties and higher critical density J_c than in Y-Ba-Cu-O and Bi-Pb-Sr-Ca-Cu-O superconductors.

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Both mullite/SiC (0.27 μm and 1.20 μm) and mullite/TiC composite ceramics were prepared by hot-pressing at 1650°C under 35 MPa for 4h. Room-temperature bending strength, Young's modulus, Vicker's hardness and fracture toughness were investigated as functions of SiC and TiC volume fractions (0-20%). Grain growth of mullite was prevented by the existence of dispersed particles (SiC, TiC) in the matrix. As a result, bending strength of both mullite/SiC and mullite/TiC composite ceramics was improved. In the case of the mullite/SiC system, bending strength increased with increasing SiC content and showed a maximum value of 604 MPa at 20 vol%, which was about 80% higher than that of monolithic mullite. On the other hand, fracture toughness of mullite/TiC ceramic composite was observed to increase from 2.65 to 3.9 MPa√(m) with the addition of 20 vol% TiC. Correspondingly, the bending strength increased from 330-410 MPa. The strengthening mechanism by thermal treatment in air was also investigated for mullite/SiC composite ceramics and it was concluded to be useful to increase bending strength. Detailed research on the microstructure showed that a Hall-Patch relationship was recognized for grain size and bending strength.

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Tensile mechanical properties of electron beam melted pure tantalum plate were investigated. Principal results obtained from the present investigation were as follows; (1) Marked yielding behaviors followed by localized flow that leads to a falling of stress and lower fracture strength were observed. (2) Strain rate dependences of electron beam melted pure tantalum were more evident than those of pure tantalum by powder metallurgy. (3) Activation energy of tensile flow showed slightly lower value than those of powder metallurgy pure tantalum. (4) Activation volume of dislocation motion showed slightly a plastic strain dependence and almost the same level value with those of powder metallurgy pure tantalum. (5) Frequency factor of the dislocation motion showed relatively higher value of 10¹⁰ to 10¹¹ s^-1 and a little effect of the plastic strain.

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The failure of microelements such as conductors in an LSI is caused mostly by the atomic-scale defects. In this study, the nucleation process of grain boundary grooving in an aluminum conductor is analyzed in terms of atomic mechanics. The motion of atoms near an intersection between grain boundary and surface near the melting temperature is simulated by molecular dynamics and the formation of grooving can be recognized for low Σ boundaries. The simulation, however, can not be applied to the grooving in a real component because the molecular dynamics can simulate the behavior of atoms in a very short period (about 10^-9 second). A Monte Carlo method to simulate it in a longer period is proposed focusing on the jumps of atoms along the surface. The formation of grooving at lower temperature is successfully simulated by the method.

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We showed in the previous paper that the distribution of rainflow range of random wave with bimodal PSD can be determined analytically from its PSD geometry. The probability density of the rainflow range can be evaluated from the central frequency ratio γ and the power ratio b. This method postulates that the geometry of the two concentrated powers is rectangular. To apply the proposed method to the random wave response from a practical two degrees of freedom system, the procedure for extracting γ and b from the PSD has to be clarified. In this paper the method for evaluating γ and b from PSD will be investigated using simulation of random response wave from a two degrees of freedom system. Finally, the procedure to evaluate the probability density of rainflow range from given differential equations of the response system will be summarized.

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This paper presents a new approach for accurate numerical evaluation of the two-dimensional hypersingular integral identity for boundary potential gradients. The scale dependence of the accuracy of numerical results, observed in calculations based on the standard C⁰ element discretization, is eliminated by applying the optimum value of a dimensionless parameter (scaling factor) that can control the errors of the finite parts or the principal values evaluated for the discretized integral identity. Numerical results for sample potential problems with mixed boundary conditions are presented and compared with corresponding analytical solutions. It is shown that the optimum value of the scaling factor can be determined through the error estimation for one-dimensional finite-part integrals with a polynomial density function and its corresponding quadratic approximation.

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Inverse analysis for an elastic structure is used to estimate the geometry or the shape for defects and the elastic properties of the structure from additional information such as experimental data of displacements, strain and velocity of the structure subjected to any mechanical loading or constraint. In the present paper, a newly developed inverse technique using genetic algorithm (GA) is presented for identifying several elliptical defects in a square plate subjected to a uni-directional load with various loading directions. The position, the size and the number of internal defects are estimated by using displacement data of the plate and GA. The influence of some parameters in GA upon the final results of inverse analysis is investigated and a new method for estimation of defects is presented.

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Solid horns for "power ultrasonics" have been evaluated and designed by considering the particle velocity and the stress distribution along their axis. And the loss of energy and the energy flow by internal friction in the horns have usually been neglected. Even if they were considered, the vibration systems were analyzed as one-dimensional systems. Therefore, in this paper, solid horns for ultrasonics are treated as three-dimensional viscoelastic bodies by using the finite-element method and introducing the concept of "power flow". Then the relationship between the loss of energy or the energy flow and the shape of the horns is studied by the FEM analysis and the experiments. The generally used solid horns were evaluated and a new shape of the solid horn was presented from the viewpoint of energy transfer.

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Ultrasonic wave velocities in a plastically deformed medium are known to be dependent upon its microstructual material properties, e. g., crystalline structure, texture, distributions of residual stress and vacancy. Therefore, the authors proposed the theoretical modeling of an ultrasonic nondestructive method to evaluate plastically deformed states ; we obtained good agreement between the numerical and experimental results on an aluminum alloy specimen subjected to uniaxial tension, and successively reported the influence of annealing effect upon the plastic anisotropy and the correlation between the Lankford's value and the shapes of yield surface of the aluminum alloy. The purpose of the present paper is to verify the subsequent yield surfaces estimated by the ultrasonic evaluation method, in which the internal variables of the anisotropic distortional yield model were determined to achieve a good fit for the experimental results of the longitudinal and transverse wave velocity changes under the plastic deformation, compared with the experimental yield surfaces of the aluminum alloy tested in combinations of tension or compression and torsion.

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In the present paper, suitable properties of the acoustic lens for the complex V(z) curve analysis using a scanning acoustic microscope are suggested. First, it is confirmed that the amplitude and the phase of the transfer function of the lens can be calculated theoretically by the transmittance function at the tip of the lens and sound field on back focal plane of the lens. To investigate the effect of the lens properties on measuring wave velocities, critical angles of waves for four kinds of glass samples are inspected by two different lenses. As a result, it is found that the transfer function of the lens in which the large amplitude decreases gradually with the normalized wave numbers, is superior in inspecting critical angles of longitudinal and transverse waves. To inspect the apparent critical angle of Rayleigh wave, it is preferable to use the lens which has the stable phase in the transfer function with respect to the normalized wave numbers.

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It is essential to clarify the impact force being applied to plastic film when it is dropped, time of dropping, since in most cases, bursting of packing bag may be caused by drop impact. In particular, while the flexible film used in fluid package is a low-cost material and provides an ideal packing form having maximum functions despite using a small amount of plastics, it has several disadvantages such as high dependencey on temperature/humidity and low impact strength, which are common weak points of plastics, due to its thinner composite structure when laminated with single-layer films. On that basis, the impact force being applied to film when it is dropped was reproduced by tensile impact testing, the relation between bursting and the tensile impact strength of film was examined, and flexible packaging technology as a safe and economical method has been established.

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The consumption of plastic containers used for packing foods was steadily increased in recent years, and so was the percentage in industrial waste. Attracting attention under these circumstances is the composite film with which the consumption of plastics can be reduced to 1/3-1/10 in weight of that required for hard plastic containers and which can be compressed to small volume after use. The subject focused up here relates to flexible packages which facilitate economical utilization of plastics made from limited resources of petroleum and effective reduction of plastic wastes. In particular, dynamic experiments were conducted to determine the causes of breakage during transportation of the packages containing liquid, for different viewparameters points including temperature and internal pressure of contents, and to clarify interrelationships among physical characteristics of film, types of contents and external force, in an effort to establish safe and economical transportation of products.

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There are many optimization problems in which the objective function has local minima. If we apply gradient methods to such problems, we must repeat many calculations with different initial points. Furthermore, it is not guaranteed that the solution is a true global minimum, unless the initial points are numerous and widely scattered. Recently, genetic algorithm (GA) has been receiving strong interest as a tool for solving such problems. It is a population-and generation-based probabilistic search strategy. The global minimum can be found with higher probability by GA than by deterministic methods. However, it takes a long time for convergence. To overcome those difficulties, an effective method is developed by combining GA and the clustering technique. This method consists of the following procedures. (1) Perform GA up to an appropriate generation. There is no need for calculation until convergence is obtained. (2) Apply the clustering technique to the results of (1) and determine the cluster centroids. (3) Find the minima by certain gradient methods starting with the cluster centroids obtained in (2), and take the smallest result as the optimal one. Two sample problems are solved to demonstrate the applicability of the proposed method.

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An optimum design technique of plate and shell adhered structures is suggested for an isoparametric shell connecting element using the penalty function method. The connecting condition at the junction parts is assembled to the potential energy functional by the penalty parameter and the interpolating function of displacements. For the optimum design of the structures with junction parts, a design sensitivity analysis formulation for the adhesive special element is developed. The suggested technique is applied to the minimum weight design of isotropic and composite laminated plates with a stiffener subjected to stress constraints, and the validity of the technique is discussed.

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In this paper, the 3-D molecular structure of actin monomer (G-actin) is studied by using the molecular mechanics analysis code, AMBER, which was developed by Kollman et al. . Actin and myosin molecules come together to construct the actomyosin system, which generates the motility assay to induce the whole muscle contraction. Several constitutive models for the muscle material exist under the theoretical basis of continuum mechanics, but the contraction process model is still incomplete. Therefore, we focus the investigation on the clarification of the contraction mechanism at the microlevel, because, in this decade there has been great progress in computational chemistry and protein engineering at the molecular level. The conformation of the actin molecule in vivo should take the optimum structure to generate the relative sliding between actin and myosin filaments under ATPase hydrolysis. At this moment the molecular structure of actin may be optimized in the molecular mechanics sense. We employ the molecular structure data of G-actin determined experimentally by Holmes et al. in 1990. The minimum-energy conformations of G-actin in four cases, e. g., with ATP or without ATP, and proK-actin-cut off between Met-47 and Gly-48- or normal actin, were determined by the steepest-descent method and the conjugate-gradient method in the molecular mechanics calculation. We investigate the differences of the conformation and potential energies among these four cases to characterize the atom structure and mechanical properties.

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The mechanical remodeling of bone is a kind of adaptation and is performed to ragulate the stress/strain in the tissue in response to the changing mechanical environment by tissue growth/atrophy. This article proposes a phenomenological model of mechanical remodeling of bone with tissue structure taking into consideration the residual stress. The lattice continuum model is used to represent the bone tissue structure such as trabecular architecture of the cancellous bone. The basic idea concerning the mechanical remodeling, taking into consideration the residual stress in the previous report, is extended to the continuum with the internal structure. A remodeling rate equation of the tissue structure is described so as to result the equistress state at the remodeling equilibrium as an optimality of the bone structure at steady state. A case study of a long bone under bending moment shows basic features of the proposed model of the stress regulation process. Remodeling simulation for the vertebra under repetitive bending and compression demonstrates the trabecular density and residual stress distribution which coincide with the experimental observations.

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This paper describes a fundamental method for easy search of several adaptive solutions for structural design problems with variable design constraints. In this method, the structures are composed of many cell elements of which the mechanical properties, shape and other design parameters are coded in binary data. The structural design is achieved using a basic rule given between binary data of cell elements. This method is called "cell element method (CEM)" and is applied to the simple design example of a truss structure. The numerical results are compared with the corresponding solutions obtained using the genetic algorithms.

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