A sensitivity based parameter identification method is presented to detect the damage of existing structures, using applied sets of static forces at one subset of degrees of freedom and measured displacements at a subset of degrees of freedom that may overlap completely, partially, or not at all. The algorithm follows an output error approach, which minimizes the deviation between a measured and a theoretical displacement, in lieu of the commonly used force error function. An iterative scheme is developed utilizing a first order Taylor series expansion to linearize the associated non linear problem. The algorithm automatically adjusts the structural element stiffness parameters, in order to improve the comparison between a measured and a theoretical response in an optimal way. The measured input required in the present study is artificially generated. The effect that a noisy displacement measurement has on an identification procedure is also studied. A procedure is also identified, in order to select the limited number of DOF required to perform successful parameter identification, reducing the impact of measurement errors on the identified parameters. The algorithm is elucidated by a numerical example on frame structures.

In the present work, a displacement-based high-order shear deformation theory is introduced for the static response of functionally graded plates. The present theory is variationally consistent and strongly similar to the classical plate theory in many aspects. It does not require the shear correction factor, and gives rise to the transverse shear stress variation so that the transverse shear stresses vary parabolically across the thickness to satisfy free surface conditions for the shear stress. By dividing the transverse displacement into the bending and shear parts and making further assumptions, the number of unknowns and equations of motion of the present theory is reduced a and hence makes them simple to use. The material properties of the plate are assumed to be graded in the thickness direction according to a simple power-law distribution in terms of volume fractions of material constituents. The equilibrium equations of a functionally graded plate are given based on the higher order shear deformation theory. The numerical results presented in the paper are demonstrated by comparing the results with solutions derived from other higher-order models found in the literature and the present numerical results of Finite Element Analysis (FEA). In the numerical results, the effects of the grading materials, lay-up scheme and aspect ratio on the normal stress, shear stress and static deflections of the functionally graded sandwich plates are presented and discussed. It can be concluded that the proposed theory is accurate, elegant and simple in solving the problem of the bending behavior of functionally graded plates.

In this paper static and dynamic response of nano-tweezers composed of two carbon nanotube (CNT) arms are investigated. Taking into account a continuum model and considering the electrostatic actuation as well as the presence of the van der Waals forces, the static nonlinear equations are solved by a step by step linearization and Galerkin projection method. Simulating the closing dynamics of a specific nano-tweezer, the effective diameters of its nanotube cantilevers are specified and compared with existing experimental data. Then by imposing a step DC voltage and taking into account the inertia effects, dynamic responses and pull-in conditions of nano-tweezers are studied. In the analyses, the effects of various parameters such as initial gap, nanotube length and diameter on the pull-in conditions are investigated. Effects of damping and asymmetric stiffness's of the arms on the pull-in voltages of a nano-tweezer are also reported. Comparing the results with the published experimental data shows that the use of continuum model and employing the Galerkin based step by step linearization method (SSLM) could effectively simulate the response of nano-tweezers.

Background and Aim: The aim of the present study was to investigate the effect of the Hand Static Rest Splint on reducing the pain and other compliance of Rheumatoid Arthritis (RA). Materials and Methods: In the present clinical trial, 12 patients, aged 35-50 (average: 39 years) with RA, referring to the Occupational Therapy Unit of Taleghani hospital and meeting America College of Rheumatology diagnostic criteria, were included. Visual Analogue Scale (VAS) was administered and swelling, tenderness and morning stiffness were assessed. Moreover, assessments of active range of motion using goniometry and grip strength with Jamar dynamometer in both hands were performed. Statistical analysis of data was performed using t-test and Mann-Whitney Test for two independent samples and willcoxon tests and paired t-test for paired samples run in SPSS, version 18. The level of significance was set at p˂ 0. 05. Results: The findings showed that the Static Rest Splint led to improvement in the wrist range of motion (flexion p=0/005, extension p=0/03) when the two groups were compared, but it did not have a significant effect on Morning Stiffness (p=1), pain (p=0/1), Swelling (p=0/06), and Tenderness (p=0/2). However, when compared between after and before intervention in hand with splint, pain (p=0/02) and wrist range of motion (p=0/004) improved. Conclusion: Based on the findings of the current study, and since using splints only improve range of motion in the wrist compared between two groups and pain relief before and after the intervention, it seems that using hand Static Rest Splint to reduce other symptoms need further investigation and also given that the use of this position without stress on the tendon can be effective in reducing the causes deformity, further studies are needed to more delineate these points.

Analysis methods proper to the level of design and the type and configuration of the dam are used for evaluating the concrete dam response under static and dynamic loadings. The amount of tensile stresses that occur inside the dam body has been very important to assess the safety of suchlike structures during earthquake. In this study, two- dimensional finite element model of the tallest monolith of Javeh RCC dam was provided for the purpose of analysis. The hydrodynamic effect of the reservoir was applied by solving the wave equation. The assumptions of water compressibility and structure deformation were used in the analysis. The foundation rock underlying the dam and reservoir bottom was modeled as a homogeneous, isotropic and viscoelastic half- plane. Static analysis results show that the compressive stresses exist in the whole of the dam body. In the dynamic analysis subject to maximum credible earthquakes, principal tensile stresses of some elements at the downstream face of the dam are greater than allowable tensile stress of RCC. Normal tensile stresses are less than the tensile strength of RCC layers.

Analysis of road pavements responses such displacements، strains and stresses resulting from imposed impulsive loads، is one of the most important issues in pavement design. Various methods such as finite element، boundary element etc. can be used for analysis of this problem، but، as in all matters، the main goal is to reach high accuracy while spending less time for analysis، in this research، a new method of differential quadrature method (DQM) is used. In most studies implemented to date، the behavior of flexible pavement is considered as an elastic material but the asphalt concrte (AC) layer on top of the flexible pavement، behave as a viscoelastic material. The theory of viscoelasticity is an old subject، but its application in flexible pavement modeling، due to the time-dependent behavior of the viscoelastic materials and also the layered structure of flexible pavement، complicates the modeling. In this paper، first، with incremental integration of Boltzmann's correspondence principle and using the generalized Wiechert model for viscoelastic behavior، incremental equilibrium equations of 3D axisymmetric condition are obtained and discritized in spatial domains using DQM. Then، in order to verificate، three-dimensional multilayered viscoelastic problems are modeled using Differential Quadrature Element method (DQEM)، and the results of this method are compared with analytical solutions and finite element method (ABAQUS software) results. In the end، a flexible pavement structure with viscoelastic behavior under sinusoidal loading is simulated quasi-statically، and the effects of the viscoelastic response of the pavement under loading with different speed of vehicles as well as several performance indicators such as tensile stress and tensile strain under the AC layer، vertical stress on the subgrade، and vertical displacement of the pavement surface، which are commonly used in the design of the pavement، are investigated.