Papers by Keyword: Shock Response

Abstract: The separation reliability and shock response of a state-of-the-art non-fracture Super-Zip separation device have been analyzed. The simulated results showed that the minimum peak value of the internal pressure for separating of the non-fracture Super-Zip separation device was quarter of the conventional Super-Zip separation device. At the same time, on account of the non-fracture separation mode, the structure near the state-of-the-art non-fracture Super-Zip separation device had lower impact acceleration responses comparing with the conventional Super-Zip separation device.

Abstract: The shock spectrum of gearbox was gotten according to German specification. And the equivalent time-domain acceleration curve was converted from shock spectrum. After the dynamic finite element model of entire gearbox was established by using the truss element, spring element and tetrahedral element, the shock response including the vibration velocity, acceleration and dynamic stress of gearbox subjected to the acceleration shock excitation were simulated. At last, the anti-shock performance of gearbox was analyzed combining with the strength criterion.

Abstract: In this paper, by using nonlinear dynamical theory and Arbitrary Lagrange Eulerian (ALE) algorithm in LS-DYNA ^3D finite element program, a method of numerical simulation is used to study dynamical response of buried gas pipeline underground shock wave of underground explosion. The simulation results shows that it is feasible for the numerical simulation method in this paper to study dynamical response of buried pipelines underground shock waves from explosion. the conclusion in this paper may provide significant reference for the risk evaluation and disaster prevention of buried gas pipeline.

Abstract: This paper proposes to model cushioning materials by combining hyperbolic tangent function and tangent function together. Based on the proposed model, the kinetics equations for cushion packaging system under excitation of half-sine acceleration pulse shock have been derived, where the rotation due to product’s eccentricity in center of mass has been taken into account. The law for coupling between rotation and translation is discussed. Numerical analysis shows that it may lead to a certain degree’s excessive packaging and thus causes waste if the rotation effect is not considered in design. The proposed model and the established kinetics equations with consideration of coupling between translation and rotation provide much better description regarding the characteristics of practical cushion packaging systems, and thus can be taken as reference in design optimization for packaging structure. The proposed approach can also be directly applied in analyzing the shock responses of packaging systems with multiple degrees of freedom.

Abstract: Survivability in shock environment is an important reliability index of silicon micro-gyroscope. Shock response of dual-mass silicon micro-gyroscope is investigated in this paper. A lumped mass model was established for the micro-gyroscope based on the characteristics of the dual-mass structure. Analytic solution to the response of the structure under shock load in a half-sine acceleration form was then acquired. The analytic solution was applied to calculate the shock response of a well designed dual-mass silicon micro-gyroscope in our laboratory, while the correctness of it was verified with finite element method (FEM) in ANSYS. The analytic solution is serviceable in reliability prediction of dual-mass silicon micro-gyroscope in shock environment.

Abstract: Gearbox system, as the main component of the marine power plant, is the closed drive unit that connects the main engine to the shaft. The operation state of the gearbox system has great influence for the safety and reliability of the ship. Shock loading is one of the most common external excitation for the ship and often destroys the devices and structures. Then, according to a mass of numerical calculations, this investigation develops some parameterizations for shock responses of the marine gearbox. The system modeling procedure is based on 3D finite element method which considers the effects of transient dynamic, geometrical nonlinear and impact/contact problems. Typical shock loads, which have the shape of double peak and triangle wave, were applied alone the three perpendicular directions on the bottom surface of the gearbox system to simulate the process of base excitation. The load can be described by two parameters: amplitude and wave length. Responses of the system were calculated with different load parameters and the maximum deformations were taken out by using Von Mises yield criterion. The relationship between shock parameters and structure stress were finally expressed by simulation data curve.

Abstract: The shock response of single freedom system was studied based on impact theory. The shear blade of some merchant shearing machine was selected as the object. The static calibration and impact load testing was carried on the object. Based on the impact theory and finite element technology, the feasibility of the testing scheme and the influence of the shock wave shape on the testing accuracy were discussed. The results show that for the shear blade, when the impact load time history is 50ms and the natural frequency is 2848Hz, there only 0.42% difference between the maximum dynamic response and the static calibrated response. So it is practicable to use the static calibrated results to decide the relationship of the impact load and strain.

Abstract: Shock response analysis of a journal-bearing system with the journal-bearing connection modeled as a spring link in radial direction and a dry contact joint respectively is presented. In the first model, the spring constants representing oil-film characteristic are determined by eight coefficients. In the second model, the friction forces are calculated using a modified Coulombs friction law. The contact detection points are the integration point and located at Gauss points. Only the contact normal pressure is treated as a Lagrange multiplier. The tangential contact stresses are calculated based on the penalty method. System’s time varying responses are obtained by FEM. A results comparison was performed between “spring link” model and “dry contact” model. The main conclusion is that stress distribution is nearly same in the system modeled by the two methods, but the amplitude in the former is smaller than that in the latter.

Abstract: This paper describes the development of a software simulation tool of discrete elements which has been developed for the purpose of investigating the dynamic response of multilayer sandwich structures that incorporate highly nonlinear crumple (buckling) elements. These structures are to be optimised as cushions in order to minimise the transmission of shocks when exposed to transient excitation, such as in a free fall. Presented results are for multilayer corrugated paperboard. A single layer was modelled as a nonlinear 2-DOF system with an additional elastoplastic element to reflect contact conditions. Numerical models of the platen and the exciter with either acceleration or displacement control were developed and applied to perform numerical compression tests of the sandwich layer at various strain rates to validate the model of a single layer. Sandwich structures were then numerically assembled and subjected to simulated impacts. The model predicted inter- and intralaminar forces, displacements, velocities and accelerations. The shock attenuation characteristics were obtained and presented as the time-acceleration-static stress maps. A postprocessor was developed to produce animations to reveal complex dynamic interactions within modelled sandwich structures.

Abstract: This paper presents some of the latest results of a research project aimed at using composite corrugated paperboard structures for protection of products against mechanical shocks and vibration during transportation and handling. Specifically, the behaviour of multi-layered corrugated paperboard (MCPB) under shock loading is investigated. Conventionally, packaging cushion design requires the determination of the maximum expected shock levels or equivalent drop which are usually determined from statistical analysis of original field measurements. With this approach, it is generally acknowledged that the cushioning element is engineered to provide adequate protection for statistically likely events but not for extreme events with low statistical likelihood. It is reluctantly accepted that, should it occur, the latter will result in damage to the product. MCPB can be formed with a broad range of compressive characteristics and with various proportions of elastic and plastic behaviour. The objective of this experimental investigation was to determine the optimum elastic/plastic proportion to extend the protective range to include large shock levels. The experimental results obtained include the effects of compression history on the stress-strain properties of MCPB as well as the behaviour of the material in both virgin and pre-compressed form under impulsive loads. The mechanism of deformation of the corrugations (flutes) was studied using high-speed video equipment. The complex acceleration signals produced during deformation of the composite corrugated paperboard cushions under shock loading were analysed by means of the shock response spectrum. Experiments have shown that inserting a sacrificial crumple element of virgin corrugated paperboard at the optimum contact area ratio dramatically lowers the overall level of the resulting shock response spectrum. This has the effect of increasing the allowable drop height for a limited number of extreme events. The main conclusion of the research is that MCPB in both virgin and pre-compressed forms can be combined to provide significantly enhanced protection to products against mechanical hazards during distribution.