Deflection (engineering)

About: Deflection (engineering) is a research topic. Over the lifetime, 30862 publications have been published within this topic receiving 298849 citations.

Effect of width on the stress-induced bending of micromachined bilayer cantilevers

Abstract: In this paper, the effect of cantilever width is demonstrated on the stress-induced bending of micromachined bilayer cantilevers. In previous literature, the bilayer cantilever has been modeled as a two-dimensional structure; consequently, the stress-induced bending of micromachined bilayer cantilever was considered to be independent upon the width. In this study, the fabrication and characterization of various widths of micromachined bilayer cantilever have been performed to observe the out-of-plane deformation caused by residual stresses. A finite element model has been established to analyze such a deformation. With the support of experimental and numerical results, width dependence in the stress-induced bending of micromachined bilayer cantilever has been discussed. As a result, the tip deflection of the bilayer cantilever gradually increases as the width increases until the width-to-length ratio reaches a critical value, in which the micromachined bilayer cantilever can be regarded as an infinitely wide cantilever, and any cross section along the length is in plane strain state. Furthermore, width-independent design, which exists among very wide cantilevers with various widths, has also been reported. Thus a more reliable design can be achieved.

Shear Connection Nonlinearity and Deflections of Steel–Concrete Composite Beams: A Simplified Method

Abstract: In steel and concrete composite beams, the incomplete interaction between steel profile and concrete slab leads to an appreciable increase of the beam deflections with respect to full interaction behavior. Moreover, the concrete cracking in hogging moment regions of continuous beams needs to be considered. In this paper, a finite-element procedure considering nonlinear load–slip relationship for shear connectors is presented. Such a procedure accounts for the concrete slab cracking and the resulting tension stiffening effect; it also assumes different load–slip relationships for shear connectors in cracked slab. Some experimental comparisons show the accuracy of the proposed procedure. A wide parametric analysis is performed with reference to the evaluation of deflections for simply supported composite beams. Finally, a simplified method which is able to evaluate deflections for beams with nonlinear behaving shear connection is presented.

Pull-in Instability of Micro-switch Actuators: Model Review

Abstract: The existing three widely used pull-in theoretical models (i.e., one-dimensional lumped model, linear supposition model and planar model) are compared with the nonlinear beam mode in this paper by considering both cantilever and fixed-fixed type mi cro and nano-switches. It is found that the error o f the pull-in parameters between one-dimensional lumped model and the nonlinear beam model is large because the denominator of the electrostatic force is minim al when the electrostatic force is computed at the maximum deflection along the beam. Since both the linear superposition model and the slender planar model consider the variation of electrostatic force with the beam’s deflection, these two models not o nly are of the same type but also own little error of the pull-in parameters with the nonlinear beam model, the error brought by these two models attributes to tha t the boundary conditions are not completely satisf ied when computing the numerical integration of the def lection.

Design Studies for Twist-Coupled Wind Turbine Blades

Abstract: This study presents results obtained for four hybrid designs of the Northern Power Systems (NPS) 9.2-meter prototype version of the ERS-100 wind turbine rotor blade. The ERS-100 wind turbine rotor blade was designed and developed by TPI composites. The baseline design uses e-glass unidirectional fibers in combination with {+-}45-degree and random mat layers for the skin and spar cap. This project involves developing structural finite element models of the baseline design and carbon hybrid designs with and without twist-bend coupling. All designs were evaluated for a unit load condition and two extreme wind conditions. The unit load condition was used to evaluate the static deflection, twist and twist-coupling parameter. Maximum deflections and strains were determined for the extreme wind conditions. Linear and nonlinear buckling loads were determined for a tip load condition. The results indicate that carbon fibers can be used to produce twist-coupled designs with comparable deflections, strains and buckling loads to the e-glass baseline.

Characterizing mode II delamination cracks in stitched composites

Abstract: This paper deals with characterizing the bridging mechanisms developed across delamination cracks by through-thickness reinforcement, using stitched carbon/epoxy laminates under mode II loading as a prime example. End Notched Flexure (ENF) tests are performed which show that stitching can provide stable crack growth. The bridging law, which characterizes the bridging action of the stitches, is deduced from both crack profile measurements and load vs. deflection curves. Consistent results are obtained from the two methods. The inferred laws imply that delamination cracks will commonly grow in conditions that are neither accurately nor properly described by linear elastic fracture mechanics. Large scale bridging calculations are required, in which the essential material property is the bridging traction law. The level of detail in which the law must be determined can be inferred from the sensitivity of predicted crack growth to variations in the law. It is recommended that the required parametric traction law be deduced in engineering practice from load vs. deflection data from the standard ENF (or similar) test, with due regard to selecting the notch size and other specimen dimensions to ensure that crack growth is stable in the test.