Deflection (engineering)

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

Nonlinear analysis of microstructure-dependent functionally graded piezoelectric material actuators

Abstract: In the present work, a nonlinear thermo-electro-mechanical response of functionally graded piezoelectric material (FGPM) actuators is investigated. The theoretical formulation is based on the Timoshenko beam theory with the von Karman nonlinearity (in the form of midplane stretching), and a microstructural length scale is incorporated by means of the modified couple stress theory. A power-law distribution of thermal, electrical, and mechanical properties through beam thickness (or height) is assumed. The governing equations are derived using the principle of virtual displacements. A displacement finite element model of the theory is developed, and the resulting system of nonlinear algebraic equations is solved with the help of Newton's iteration method. Numerical results are presented for transverse deflection as a function of load parameters and out-of-plane boundary conditions. The parametric effects of microstructural length scale parameter, power-law index of the material distribution across the thickness, boundary conditions, beam geometry, and applied actuator voltage on the beam response are investigated through various numerical examples. The results reveal the existence of bifurcation (or critical states) for certain types of in-plane loads. For other load types, including out-of-plane loads, the beam undergoes a unique and stable deflection path that does not contain any critical point.

A discrete particle approach to simulate the combined effect of blast and sand impact loading of steel plates

Abstract: The structural response of a stainless steel plate subjected to the combined blast and sand impact loading from a buried charge has been investigated using a fully coupled approach in which a discrete particle method is used to determine the load due to the high explosive detonation products, the air shock and the sand, and a finite element method predicts the plate deflection. The discrete particle method is based on rigid, spherical particles that transfer forces between each other during collisions. This method, which is based on a Lagrangian formulation, has several advantages over coupled Lagrangian–Eulerian approaches as both advection errors and severe contact problems are avoided. The method has been validated against experimental tests where spherical 150 g C-4 charges were detonated at various stand-off distances from square, edge-clamped 3.4 mm thick AL-6XN stainless steel plates. The experiments were carried out for a bare charge, a charge enclosed in dry sand and a charge enclosed in fully saturated wet sand. The particle-based method is able to describe the physical interactions between the explosive reaction products and soil particles leading to a realistic prediction of the sand ejecta speed and momentum. Good quantitative agreement between the experimental and predicted deformation response of the plates is also obtained.

Stiffness and deflection of steel-concrete composite beams under negative bending

Abstract: Compared with simply supported beams, continuous steel–concrete composite beams have many advantages such as higher span/depth ratio, less deflection, and higher fundamental frequency of vibration due to its higher stiffness. However, in negative bending regions near interior supports, tension in concrete is unfavorable and a complicated issue, which deserves a special study. In this paper, a mechanics model based on elastic theory was established to investigate the stiffness of composite beams in negative bending regions by considering slips at the steel beam–concrete slab interface and concrete–reinforcement interface. In order to validate this approach, a test of three composite beams with profiled sheeting under negative bending was conducted. Meanwhile, a three-dimensional nonlinear finite element (FE) analysis was conducted to investigate the general behavior of the tested specimens. In addition, a comparative analysis between results derived from the analytical model, laboratory test, and FE analys...