Deflection (engineering)

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

The effective thickness of laminated glass plates

Abstract: The flexural performance of laminated glass, a composite of two or more glass plies bonded together by polymeric interlayers, depends upon shear coupling between the glass components through the polymer. This effect is usually taken into account, in the design practice, through the definition of the effective thickness, i.e., the thickness of a monolith with equivalent bending properties in terms of stress and deflection. The traditional formulas a la Wolfel-Bennison are accurate only when the deformed bending shape of the plate is cylindrical and the plate response is similar to that of a beam under uniformly distributed load. Here, assuming approximating shape function for the deformation of laminated plates variously constrained at the edges, minimization of the corresponding strain energy furnishes new simple expressions for the effective thickness, which can be readily used in the design. Comparisons with accurate numerical simulations confirm the accuracy of the proposed simple method for laminated plates.

A large stroke, high force paraffin phase transition actuator

Abstract: An actuator that uses the volume expansion related to the solid-to-liquid phase transition of paraffin wax has been fabricated and evaluated. The actuator consists of a ring-shaped paraffin cavity confined by two joint silicon diaphragms with rigid centers. When the paraffin is melted, the resulting hydrostatic pressure deflects the joined rigid centers in one direction only. The magnitude of the deflection is primarily a function of the geometrical relation between the two diaphragms, giving the opportunity to tailor the behavior of the actuator in a large range. Conventional IC-processing techniques have been used to fabricate a prototype with a width of 68 mm and a thickness of 825 μm. The prototype attained a maximum deflection of ca. 90 μm. Loaded with 3 N it still exhibits a deflection of ca. 75 μm. The device can be used as a thermal switch.

Variable Stiffness Legs for Robust, Efficient, and Stable Dynamic Running

Abstract: Humans and animals adapt their leg impedance during running for both internal (e.g., loading) and external (e.g., surface) changes. To date, the mechanical complexity of designing usefully robust tunable passive compliance into legs has precluded their implementation on practical running robots. This work describes the design of novel, structure-controlled stiffness legs for a hexapedal running robot to enable runtime modification of leg stiffness in a small, lightweight, and rugged package. As part of this investigation, we also study the effect of varying leg stiffness on the performance of a dynamical running robot. For more information: Kod*Lab Comments BibTeX entry @article{Galloway-Journal_of_Mechanisms_and_Robots-2013, author = {Kevin C. Galloway and Jonathan E. Clark et al}, title = {Variable Stiffness Legs for Robust, Efficient, and Stable Dynamic Running}, booktitle = { Journal of Mechanisms and Robotics}, year = {2013}, month = { January}, } This work was partially supported by the NSF FIBR Grant #0425878 and the IC Postdoctoral Fellow Program under Grant no. HM158204–1−2030. This journal article is available at ScholarlyCommons: http://repository.upenn.edu/ese_papers/664 Variable Stiffness Legs for Robust, Efficient, and Stable Dynamic Running Kevin C. Galloway Wyss Institute for Biologically Inspired Engineering Harvard University Cambridge, MA 02138 Email: kevin.galloway@wyss.harvard.edu Jonathan E. Clark Department of Mechanical Engineering FAMU/FSU College of Engineering Tallahassee, FL 32310 Email: clarkj@eng.fsu.edu Daniel E. Koditschek GRASP Laboratory Department of Electrical and Systems Engineering University of Pennsylvania Philadelphia, PA, 19104 Email: kod@seas.upenn.edu Humans and animals adapt their leg impedance during running for both internal (e.g. loading) and external (e.g. surface) changes. To date the mechanical complexities of designing usefully robust tunable passive compliance into legs has precluded their implementation on practical running robots. This work describes the design of novel, structure-controlled stiffness legs for a hexapedal running robot to enable runtime modification of leg stiffness in a small, lightweight, and rugged package. As part of this investigation, we also study the effect of varying leg stiffness on the performance of a dynamical running robot.

A preliminary evaluation of carbon fibre reinforced polymer plates for strengthening reinforced concrete members.

Abstract: An experimental parameter study of the strengthening of reinforced concrete beams by bonded composite plates is presented. Plate geometry and applied load configuration are studied, revealing that bonded plates increase the ultimate capacity of beams but reduce ductility. Bonded plates are effective in carrying increased proportions of internal moment couples beyond yield of internal reinforcement. Ultimate capacity falls with reducing plate aspect ratio and beam shear span/depth ratio; shear type concrete failures were prevented by provision of sufficient internal reinforcement. Failure under low shear span/depth ratios is associated with high plate strains, while this is not always the case for beams tested under higher shear span/depth ratios. In all cases, failure was associated with relatively high longitudinal shear stresses at the adhesive-concrete interface, although the concrete failed in all tests and debonding of the adhesive from the concete was not observed. Plate end anchorage delays failure by resisting plate separation but does not increase structural stiffness until internal reinforcement has yielded. (A)