The paper formulates the closed-form stiffness equations that can be used to characterize the static, modal, and dynamic behavior of single-axis corner-filleted flexure hinges, which are incorporated into macro/microscale monolithic mechanisms. The derivation is based on Castiliagno’s first theorem and the resulting stiffness equations reflect sensitivity to direct- and cross-bending, axial loading, and torsion. Compared to previous analytical work, which assessed the stiffness of flexures by means of compliances, this paper directly gives the stiffness factors that completely define the elastic response of corner-filleted flexure hinges. The method is cost-effective as it requires considerably less calculation steps, compared to either finite element simulation or experimental characterization. Limit calculations demonstrate that the known engineering equations for a constant cross-section flexure are retrieved from those of a corner-filleted flexure hinge when the fillet radius becomes zero. The analytical model results are compared to experimental and finite element data and the errors are less than 8%. Further numerical simulation based on the analytical model highlights the influence of the geometric parameters on the stiffness properties of a corner-filleted flexure hinge.

This paper presents measurement of tensile proprieties of thermoplastics by digital image correlation method. The objectives are to characterize based on experimental data the pre-and post-yield regime of polyvinylchloride (PVC) under uniaxial tension and to investigate the rate-dependent large deformation behaviour over crosshead speeds of 1, 5 and 25 mm/min respectively. The true strain-stress curves of PVC tested with different loading speeds are experimentally obtained and based on these a phenomenological constitutive model is implemented. The theoretical material model considers the variation of strain rates due to the inhomogeneous deformation behaviour of thermoplastic polymer and includes six parameters (material constants) to be identified according to the experimental results. It can be found that the effect of the strain rate on the true stress strain curves is small for lower strain rates but cannot be ignored for higher strain rate.

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The purpose of this paper is to present some results and benefits for using the 2D Digital Image Correlation (DIC) method on the deflection determination of the V-beam thermal sensor. Therefore, the influence of the main geometrical parameters of the V-beam type thermal sensors on its deflection is evaluated. An experimental set-up was designed is order to acquire high resolution images of the deformed sensor at different temperatures. The analytical and the finite element (FE) studies that were performed on theoretical models of the V-beam sensor led to the validation of the experimental results and thus to the validation of the method.

The complications of fractures caused by osteoporosis have a mortality rate of 15-20 % in elderly people, leading to severe physical disability and long term home care [1]. Although currently, the technology that allows us to prevent osteoporosis and fractures caused by this disease exists, the statistics are concerning and can be considered basis for further research regarding this pathology of the bone tissue. This paper aims to address this issue form an engineering perspective by achieving experimental validation of a finite element model of an osteoporotic human femoral bone using strain gauge measurement for an in vitro analysis. A Computer Aided Design (CAD) model based on a CT of a human femoral bone was then used in a numerical analysis. The material constants used are taken from the literature and have been validated experimentally by strain gauge technique.