The aim of the present paper is sensitivity of shape design analysis on thermo-elastic problems using a modified semi-analytical method. The semi-analytical method is one of the efficient methods for sensitivity analysis with respect to the design variables which combines the analytical method and finite difference method. Although this method is a powerful method, however, it is sensitive to perturbation size. Complex variables method is a new novel approach which is not sensitive to disturbance and has some potential advantages over other methods. The implementation of this method in a finite element code for sensitivities calculation is straightforward, only requiring a perturbation of the finite element mesh along the imaginary axis. This study uses the combination of analytical method and complex variables method to calculate the sensitivity of thermo-elastic problems. The proposed method has both advantages of the analytical method and the complex variables method. The advantages of this method are that it is quick, accurate and simple to implement. The obtained results are compared to other methods and it is shown that the proposed method is effective and can predict the stable and accurate sensitivity results.

In this research, a new method called elastic surface algorithm is presented for inverse design of 2-D airfoil in a viscous flow regime. In this method as an iterative one, airfoil walls are considered as flexible curved beams. The difference between the target and the current pressure distribution causes the flexible beams to deflect at each shape modification step. In modification shape algorithm, the finite element equations of two-node Timoshenko beam are solved to calculate the deflection of the beams. In order to validate the proposed method, various airfoils in subsonic and transonic regimes are studied, which show the robustness of the method in the viscous flow regime with separation and normal shock. Also, three design examples are presented here, which show the capability of the proposed method.

The aim of inverse design problems is achieving a geometry corresponding to the wall target pressure distribution. One of the newest inverse design methods, was Elastic Surface Algorithm (ESA) in which the airfoil wall was modeled as a flexible curved beam and the difference between target and current pressure distributions in each iteration was the deformation factor of the airfoil wall. The first version of ESA used for the inverse design of sharp leading edge blade of axial flow compressors, is subject to oscillation, instability and divergence due to high pressure gradients on the blade leading edge. Therefore, it cannot be used for a sharp leading edge blade. The purpose of this research is to develop ESA for axial-flow compressor cascade with sharp leading edge blades. The main basis of this Improvement is paying attention to the deflection curve of the beam, which is continuous and differentiable in all points. The physical property of Timoshenko's beam in large deformations is used in the upgraded version without applying any geometric filtration to eliminate the fractures of the intermediate profiles. In order to increase the displacement of the beam at each iteration, an optimal relationship between the beam characteristics including the elasticity modulus, the thickness and width of the beam is used. Finally, the upgraded version has been validated in a few cases for subsonic inviscid flow regime. The results indicate the robustness, flexibility and high convergence rate of the upgraded ESA in the design of axial-flow compressor blades.

Investigation of natural foot behaviour shows that it’s kinetic and kinematics functions can be compared to mechanisms containing simple mechanical elements such as springs, dampers and actuators. Hence, appropriate design of this mechanism may give rise to an artificial foot that might help amputees properly. Studies show that whatever the biomechanical behavior of an artificial foot is similar to that of natural foot, where it might be utilized consuming less energy. In this study, required parameters for design of an artificial foot including spring and electromechanical actuator were examined by investigating biomechanical behavior of natural foot in walking level. Moreover, an algorithm was suggested for design of foot prosthesis and according to this algorithm, a prototype was designed and fabricated.

Introduction: Due to limitations of current treatments for degenerative disc disease, arthroplastic methods to repair the diseased disc have been proposed. The artificial disc is a mobile implant for degenerative disc replacement that attempts to lessen the degeneration of the adjacent elements following inter body fusion procedures. Because the success of artificial disc replacement depends on maintenance or restoration of the mechanical function of the intervertebral disc, it is useful to study the initial mechanical performance of the disc after implantation in the spine.Materials and Methods: A three-dimensional finite element model of the L3–L4 disc was analyzed. The model took into account the material nonlinearities and it imposed different loading conditions. In this study, we validated the model by comparison of its predictions with several sets of experimental data, we determined the optimal Young’s modulus as well as the Poissan ratios for the artificial disc under different loading conditions.Results: The artificial disc was subjected to three loading conditions: 1) compression, 2) bending and 3) torsion. In each case, optimum elastic parameters were determined. Then, by using the root mean square method, optimum parameters for all loading conditions (and therefore minimum error) were calculated.Discussion and Conclusion: The results of this study suggest that a well-designed elastic arthroplastic disc preferably has Young’s modulus values of 18.63 MPa and 1.19 MPa for the annulus and nucleus sections, respectively. Elastic artificial disc with such properties can then achieve the goal of restoring the disc height and mechanical function of a normal disc under different loading conditions.

A recently proposed meshless method, which is called the radial basis point interpolation method (RBPIM), is used for the mechanical analysis of reinforced soils. The media of reinforced soil is divided into three parts: soil, reinforcement and interface layer. The displacement field in each part is constructed by point interpolation. A code has been developed based on RBPIM and the validity of this code has been investigated by solving some examples at the end of the paper.

Abstract: The main aim of this study is to provide an algorithm for design of flexible manipulators. The distributed-lumped arm was modeled by means of transfer matrix method In this model gross motions and small motions was separated in frequency domain: This model is capable of providing us with useful information on naturalfrequencies, eigenvalues, frequency response, modal shapes and impulse response in deflection, slope, moment and shear force state variables. The above mentioned information was used to study arms with two links or one link with lumped mass. This study shows the limitations caused by arm flexibility over joint control and operation of the arm. Stiffness and strength constraints are taken into observed simultaneously. An algorithm isproposed to design the flexible arm. This algorithm combines the geometry, material and task of the arm for optimal operation.Finally, a computer program is developed and used to display the extensive analysis information in a compactform.

The statistical studies indicate that diseases, accidents and wares are the principal causes to increase the number of amputees in the world. These studies also show that the most of mutilation disabilities are related to musculoskeletal. Obesity, sedentary, lack of proper exercise as well as the risk of some diseases, cause weaken in knee muscles and other difficulties of this hand. As a consequence, the knee muscles can't apply a mighty torque to accomplish knee motion. The objective of this study is to propose a proper solution to improve the life quality of those who suffer from weak knees.in this study, by investigating the biomechanical behavior of a healthy foot in a normal gait, the indispensable power which can enforce a 50% weak Knee to achieve the same gait can be calculated. To naturalize the mentioned knee, a new control-active orthosis is designed. The proposed design is specified by an electromechanical actuator and an elastic component articulated in a light weight four-bar mechanism. Its mechanical behavior is tested in a simulated walking gait and the optimum value of elastic coefficient is estimated as 7KN/m. In this case, the maximum torque applicable to knee joint has increased by 34 per cent.

In this paper, solution of inverse problems in a plane linear elastic bodies are investigated. In recent years, many studies have been conducted to develop effective approaches for damage detection in structural components. The efforts made over the last decades to overcome the mathematical challenges encountered in non-linear inverse problems may be categorized in two procedures: traditional methods, and qualitative methods. Although satisfactory results can be obtained using traditional approaches, they impose long reconstruction times associated with necessity of an accurate initial guess. These schemes require a priori information that may not be necessarily available. Consequently, the mentioned limitations have led to the conceptually distinct class of inverse scattering solutions, known as “, qualitative methods. ”,These methods are based on non-iterative obstacle reconstruction from far-and/or near-field measurements of the scattered field which avoids incorrect model assumption. Qualitative methods may be considered as probe/sampling methods such as linear sampling method, topological sensitivity, factorization method, and point source method, which seek to determine the geometric properties of scatterers. In this regard, the LSM and the FM introduced in the inverse scattering literature of far-field acoustics for the first time, are particularly attractive. This is due to the abilities of these methods to provide accurate reconstruction of the location and shape of the unknown scatterer from measurements of near-or far-field patterns, by monitoring the behavior of the norm of regularized solution. This norm is bounded inside the targets and unbounded elsewhere. Moreover, the most interesting feature of qualitative methods is that they do not require a priori information/assumption on the scatterer and/or the investigation domain. In addition, these methods may handle multiple scatterers as easily as single ones. Furthermore, these methods involve relatively low computational cost and can be applied to various types of defects such as non-convex and not-connected ones. For this purpose, sampling method in frequency domain is introduced for cavity/crack detection in a structural element such as plate. This goal is followed by partitioning the investigated region into an arbitrary grid of sampling points, in which a linear equation is solved. The main idea of the linear sampling method is to search for a superposition of differential displacement fields which matches with a prescribed radiating solution of the homogeneous governing equation in Ω, (D), for each sampling point. Although this method has been used in the context of inverse problems such as acoustics, and electromagnetism, there is no specific attempt to apply this method to identification of crack/cavities in a structural component. This study emphasizes the implementation of the sampling method in the frequency domain using spectral finite element method. A set of numerical simulations on two-dimensional problems is presented to highlight many effective features of the proposed qualitative identification method.

Background and aim: Dental irreversible hydrocolloid (Alginate) is a major dental used world wide in many clinical procedures. The purpose of this study was to investingate the dimensional stability after prolonged storage of Alginate Elastic Chromo. This study was carried out in 2008 in Azad Islamic university.Method and Material: This experimental study was carried out by using labratory metal master model that contained two dies.20 impression were taken for master model by Alginate Elastic Chromo The four storage conditions were as follow: 0/5 hours, 24 hours , 48 hours, 120 hours, stone model were poured. Die's height, diameter and distance between dies were measured by profile projector and compared with labratory model by use ANOVA test.Results: There is no significant different between of four times casting. Height & distance dimensional change were less than 1/5% (Max distoration after 24 hours) but diameters were more than 1/5%.Conclusion: Alginate Elastic Chromo was not dimensionally stable over a 5 day period ( 120 hours). However, no effect of the times on dimensional change.