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Deflection (engineering)

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


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Patent
18 Jan 2002
TL;DR: In this paper, a deflection element span is provided, as-fabricated, curved in one of the two stable positions and in a mechanically unstressed condition along the length of the span.
Abstract: A bistable structure provided by the invention is characterized as including a deflection element that has mechanically constrained end points and a compliant span between the end points that is substantially free to deflect between two stable positions when a force is applied at a point along the span. The deflection element span is provided, as-fabricated, curved in one of the two stable positions and in a mechanically unstressed condition along the length of the span. The as-fabricated curve of the deflection element span includes a curve maxima at a point along the span length that is at least about 1/4 of the span length from the end points of the span. The deflection element span is constrained to substantially prohibit development of a second bending mode that is characteristic for the span as the element deflects between the stable positions.

118 citations

Journal ArticleDOI
TL;DR: In this article, modified couple stress theory is used to model the size effect on the static pull-in instability of electrostatic nanocantilevers in the presence of dispersion (Casimir/van der Waals) forces.
Abstract: An electromechanical beam-type nano-actuator is one the most important smart nanostructures. In this paper, modified couple stress theory is used to model the size effect on the static pull-in instability of electrostatic nanocantilevers in the presence of dispersion (Casimir/van der Waals) forces. The monotonically iterative method (MIM) and homotopy perturbation method (HPM) are employed to solve the nonlinear constitutive equation of the nanostructure as well as numerical methods. Furthermore, a lumped parameter model is developed to explain the size-dependent pull-in performance of the nano-actuator. The basic engineering design parameters such as critical tip deflection and pull-in voltage of the nanostructure are computed. It is found that dispersion forces decrease the pull-in voltage and deflection of the nano-actuator at sub-micrometer scales. On the other hand, the size effect can increase the pull-in parameters of the nano-actuators. The results indicate that the proposed analytical solutions are reliable for simulating nanostructures at sub-micrometer ranges.

118 citations

Book ChapterDOI
TL;DR: In this article, the fracture mechanics approach to fatigue crack growth may be extended by the use of the J-integral concept, so that large scale plasticity effects are included.
Abstract: Fatigue crack growth rate data are obtained for center cracked specimens of A533B steel subjected to elastic-plastic cyclic loading. Cyclic J-integral values estimated from load versus deflection hysteresis loops are correlated with these growth rate data. The relationship obtained is in agreement with previous elastic-plastic data on compact specimens and also with linear elastic data on large size compact specimens. These experimental data suggest that the fracture mechanics approach to fatigue crack growth may be extended by the use of the J-integral concept, so that large scale plasticity effects are included.

118 citations

Journal ArticleDOI
TL;DR: In this article, the authors examined the deflection/penetration behavior of dynamic mode-I cracks propagating at various speeds towards inclined weak planes/interfaces of various strengths in otherwise homogeneous isotropic plates.
Abstract: We examine the deflection/penetration behavior of dynamic mode-I cracks propagating at various speeds towards inclined weak planes/interfaces of various strengths in otherwise homogeneous isotropic plates. A dynamic wedge-loading mechanism is used to control the incoming crack speeds, and high-speed photography and dynamic photoelasticity are used to observe, in real-time, the failure mode transition mechanism at the interfaces. Simple dynamic fracture mechanics concepts used in conjunction with a postulated energy criterion are applied to examine the crack deflection/penetration behavior and, for the case of interfacial deflection, to predict the crack tip speed of the deflected crack. It is found that if the interfacial angle and strength are such as to trap an incident dynamic mode-I crack within the interface, a failure mode transition occurs. This transition is characterized by a distinct, observable and predicted speed jump as well as a dramatic crack speed increase as the crack transitions from a purely mode-I crack to an unstable mixed-mode interfacial crack.

118 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202247
20211,006
20201,140
20191,262
20181,195
20171,215