scholarly journals Three-Dimensional Shock Spectrum of Critical Component for Nonlinear Packaging System

2011 ◽  
Vol 18 (3) ◽  
pp. 437-445 ◽  
Author(s):  
Jun Wang ◽  
Zhi-Wei Wang ◽  
Li-Xin Lu ◽  
Yong Zhu ◽  
Yong-Guang Wang
Keyword(s):  
System Parameter ◽  
Damping Ratio ◽  
Three Dimensional ◽  
Low Frequency ◽  
Frequency Parameter ◽  
Critical Component ◽  
Packaging System ◽  
System A ◽  
Parameter Ratio ◽  
Shock Response

To evaluate the shock characteristics of critical component for a nonlinear packaging system, a new concept of three-dimensional shock spectrum was proposed. Three key coordinate parameters, such as the nondimensional pulse duration, the frequency parameter ratio and the ratio of the maximum response acceleration to the peak pulse acceleration, were governed in a novel dynamical mathematical model. It is shown that the shock response of critical component is weakened owning to the decrease in the defined system parameter. Furthermore, at low frequency parameter ratio, the enhancement of the damping ratio of the critical component leads to the decrease in the peak of the shock response, which can also be reduced by the increase in damping ratio of cushioning pad at both lower and higher frequency parameter ratios. The discussion and analysis provide some insights into the design of cushioning packaging as well.

scholarly journals The Shock Characteristics of Tilted Support Spring Packaging System with Critical Components

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
An-Jun Chen
Keyword(s):  
Frequency Ratio ◽  
Response Spectrum ◽  
Three Dimensional ◽  
Frequency Parameter ◽  
Mass Ratio ◽  
Packaging System ◽  
Parameter Ratio ◽  
Shock Response ◽  
Shock Response Spectrum ◽  
Critical Components

The nonlinear dynamical equations of tilted support spring packaging system with critical components were obtained under the action of half-sine pulse. To evaluate the shock characteristics of the critical components, a new concept of three-dimensional shock response spectrum was proposed. The ratio of the maximum shock response acceleration of the critical components to the peak pulse acceleration, the dimensionless pulse duration, and the frequency parameter ratio of system or the angle of tilted support spring system were three basic parameters of the three-dimensional shock response spectrum. Based on the numerical results, the effects of the peak pulse acceleration, the angle of the tilted support spring, the frequency parameter ratio, and the mass ratio on the shock response spectrum were discussed. It is shown that the effects of the angle of the tilted support spring and the frequency ratio on the shock response spectrum are particularly noticeable, increasing frequency parameter ratio of the system can obviously decrease the maximum shock response acceleration of the critical components, and the peak of the shock response of the critical components can be decreased at low frequency ratio by increasing mass ratio.

Dropping damage evaluation for a hyperbolic tangent cushioning system with a critical component

2011 ◽  
Vol 18 (10) ◽  
pp. 1417-1421 ◽  
Author(s):  
Jun Wang ◽  
Fang Duan ◽  
Jiu-hong Jiang ◽  
Li-xin Lu ◽  
Zhi-wei Wang
Keyword(s):  
Boundary Surface ◽  
Frequency Parameter ◽  
Damage Evaluation ◽  
Critical Component ◽  
Hyperbolic Tangent ◽  
Damage Potential ◽  
Packaging System ◽  
System A ◽  
Parameter Ratio ◽  
Good Agreement

A new concept of dropping damage boundary surface is proposed to evaluate the dropping damage of a critical component for a hyperbolic tangent nonlinear packaging system. A novel dynamic model is established to analyze the effect of three key coordinate parameters, i.e., the non-dimensional dropping shock velocity, the frequency parameter ratio and the defined system parameter, on dropping damage potential. An experiment, which showed good agreement, was conducted to verify the theory proposed.

Combined Shock Response Spectrum of Cubic Nonlinear Stacking Packaging System

2011 ◽  
Vol 66-68 ◽  
pp. 245-249
Author(s):  
Jiu Hong Jiang ◽  
Jun Wang
Keyword(s):  
Pulse Duration ◽  
System Parameter ◽  
Response Spectrum ◽  
Damping Ratio ◽  
Bottom Layer ◽  
Dynamical Equations ◽  
Packaging System ◽  
Acceleration Pulse ◽  
Shock Response ◽  
Shock Response Spectrum

The shock characteristics of a cubic nonlinear stacking packaging system were investigated under the action of half-sine acceleration pulse. The dynamical model of the system was developed, and the numerical results of the dynamical equations were obtained. Based on the results, a new concept of combined shock response spectrum was proposed to describe the shock characteristics of cubic stacking packaging system, focusing more on the maximum of the peak response acceleration of all products at all sensitive frequency since the damage of stacking packaging system occurs when any of the products was damaged. And it’s found that the combined shock spectrum is always made up of the shock spectrum of the bottom layer at lower dimensionless pulse duration and the shock spectrum of the top layer at higher dimensionless pulse duration. Then, the effect of the peak pulse acceleration, the defined system parameter, the damping ratio of cushioning pad in addition to the number of stacking layers on the combined shock spectrum of the system was discussed. It’s shown that all of their effect are noticeable. The results lead to some insights into the design of cushioning packaging.

scholarly journals Damage Evaluation of Critical Components of Tilted Support Spring Nonlinear System under a Rectangular Pulse

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Ningning Duan ◽  
Meng Hao ◽  
Anjun Chen
Keyword(s):  
Nonlinear System ◽  
Damping Ratio ◽  
Damage Zone ◽  
Boundary Surface ◽  
Rectangular Pulse ◽  
Frequency Parameter ◽  
Mass Ratio ◽  
Dynamical Equations ◽  
Parameter Ratio ◽  
Critical Components

Dimensionless nonlinear dynamical equations of a tilted support spring nonlinear packaging system with critical components were obtained under a rectangular pulse. To evaluate the damage characteristics of shocks to packaged products with critical components, a concept of the damage boundary surface was presented and applied to a titled support spring system, with the dimensionless critical acceleration of the system, the dimensionless critical velocity, and the frequency parameter ratio of the system taken as the three basic parameters. Based on the numerical results, the effects of the frequency parameter ratio, the mass ratio, the dimensionless peak pulse acceleration, the angle of the system, and the damping ratio on the damage boundary surface of critical components were discussed. It was demonstrated that with the increase of the frequency parameter ratio, the decrease of the angle, and/or the increase of the mass ratio, the safety zone of critical components can be broadened, and increasing the dimensionless peak pulse acceleration or the damping ratio may lead to a decrease of the damage zone for critical components. The results may lead to a thorough understanding of the design principles for the tilted support spring nonlinear system.

Unsteady Vibration of a Gas Turbine Compressor Blade at Subsonic Near-Stall Conditions

2013 ◽  
Author(s):  
Kazuyuki Yamaguchi ◽  
Yasuo Takahashi
Keyword(s):  
Mach Number ◽  
Modal Analysis ◽  
Natural Frequency ◽  
Damping Ratio ◽  
Three Dimensional ◽  
Low Frequency ◽  
Frequency Component ◽  
Blade Vibration ◽  
Aerodynamic Damping ◽  
Frequency Components

Cascade wind tunnel tests were conducted to clarify unsteady blade vibration characteristics near stall conditions. An oscillating strain and pressure on a blade surface were measured. An aerodynamic damping ratio was also measured using the sweep excitation method and the operational modal analysis. Moreover, an unsteady blade vibration response and aerodynamic damping ratios were calculated using a three-dimensional computational fluid dynamics and a three-dimensional structural finite element method. As a result of the experiments, the natural frequency component oscillated by the broadband frequency component of the fluid force was dominant in the stress, while the discrete low frequency components appeared in the pressure. The amplitudes of the stress and pressure increased when the Mach number or the incidence increased. As a result of the calculations, the discrete low frequency components appeared in the pressure, and those components and the natural frequency components appeared in the stress. The experimental and calculation results of the stress amplitude were generally in agreement. The measured damping ratios increased when the Mach number increased. The dispersion of the measured damping ratio using the operational modal analysis was small. The calculated damping ratio was 1.3–1.8 times larger than the measured result.

scholarly journals Li–He’s modified homotopy perturbation method coupled with the energy method for the dropping shock response of a tangent nonlinear packaging system

2020 ◽  
pp. 146134842091445
Author(s):  
Qiu-Ping Ji ◽  
Jun Wang ◽  
Li-Xin Lu ◽  
Chang-Feng Ge
Keyword(s):  
Perturbation Method ◽  
Energy Method ◽  
Homotopy Perturbation Method ◽  
Packaging System ◽  
Homotopy Perturbation ◽  
System A ◽  
Runge Kutta Method ◽  
Accuracy Comparison ◽  
Shock Response ◽  
Maximal Displacement

This paper couples Li–He’s homotopy perturbation method with the energy method to obtain an approximate solution of a tangent nonlinear packaging system. A higher order homotopy equation is constructed by adopting the basic idea of the Li–He’s homotopy perturbation method. The energy method is used to improve the maximal displacement and the frequency of the system to an ever higher accuracy. Comparison with the numerical solution obtained by the Runge–Kutta method shows that the shock responses of the system solved by the new method are more effective with a relative error of 0.15%.

scholarly journals Towards Fully Autonomous UAVs: A Survey

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6223
Author(s):  
Taha Elmokadem ◽  
Andrey V. Savkin
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Autonomous Navigation ◽  
Great Part ◽  
Three Dimensional ◽  
Human Interaction ◽  
Critical Component ◽  
System A ◽  
Aerial Vehicles ◽  
Recent Developments ◽  
Aerial Vehicle

Unmanned Aerial Vehicles have undergone rapid developments in recent decades. This has made them very popular for various military and civilian applications allowing us to reach places that were previously hard to reach in addition to saving time and lives. A highly desirable direction when developing unmanned aerial vehicles is towards achieving fully autonomous missions and performing their dedicated tasks with minimum human interaction. Thus, this paper provides a survey of some of the recent developments in the field of unmanned aerial vehicles related to safe autonomous navigation, which is a very critical component in the whole system. A great part of this paper focus on advanced methods capable of producing three-dimensional avoidance maneuvers and safe trajectories. Research challenges related to unmanned aerial vehicle development are also highlighted.

Other topics

2018 ◽  
Author(s):  
Ted Janssen ◽  
Gervais Chapuis ◽  
Marc de Boissieu
Keyword(s):  
Photonic Crystals ◽  
Crystal Morphology ◽  
Three Dimensional ◽  
Icosahedral Quasicrystal ◽  
Crystal Surfaces ◽  
Decagonal Quasicrystal ◽  
System A ◽  
Fundamental Law ◽  
Quasiperiodic Systems ◽  
Aperiodic Crystals

The law of rational indices to describe crystal faces was one of the most fundamental law of crystallography and is strongly linked to the three-dimensional periodicity of solids. This chapter describes how this fundamental law has to be revised and generalized in order to include the structures of aperiodic crystals. The generalization consists in using for each face a number of integers, with the number corresponding to the rank of the structure, that is, the number of integer indices necessary to characterize each of the diffracted intensities generated by the aperiodic system. A series of examples including incommensurate multiferroics, icosahedral crystals, and decagonal quaiscrystals illustrates this topic. Aperiodicity is also encountered in surfaces where the same generalization can be applied. The chapter discusses aperiodic crystal morphology, including icosahedral quasicrystal morphology, decagonal quasicrystal morphology, and aperiodic crystal surfaces; magnetic quasiperiodic systems; aperiodic photonic crystals; mesoscopic quasicrystals, and the mineral calaverite.

scholarly journals Evolution of a narrow-band spectrum of random surface gravity waves

2003 ◽  
Vol 478 ◽  
pp. 1-10 ◽  
Author(s):  
KRISTIAN B. DYSTHE ◽  
KARSTEN TRULSEN ◽  
HARALD E. KROGSTAD ◽  
HERVÉ SOCQUET-JUGLARD
Keyword(s):  
Three Dimensional ◽  
Low Frequency ◽  
Three Dimensions ◽  
Band Spectrum ◽  
Nls Equation ◽  
Random Surface ◽  
Narrow Bandwidth ◽  
Quasi Stationary State ◽  
The Stability ◽  
Three Dimensional Simulations

Numerical simulations of the evolution of gravity wave spectra of fairly narrow bandwidth have been performed both for two and three dimensions. Simulations using the nonlinear Schrödinger (NLS) equation approximately verify the stability criteria of Alber (1978) in the two-dimensional but not in the three-dimensional case. Using a modified NLS equation (Trulsen et al. 2000) the spectra ‘relax’ towards a quasi-stationary state on a timescale (ε2ω0)−1. In this state the low-frequency face is steepened and the spectral peak is downshifted. The three-dimensional simulations show a power-law behaviour ω−4 on the high-frequency side of the (angularly integrated) spectrum.

Fabrication of Three-Dimensional Micro-Structures with Two-Photon Absorption by Femtosecond Laser

2006 ◽  
Vol 532-533 ◽  
pp. 568-571
Author(s):  
Ming Zhou ◽  
Hai Feng Yang ◽  
Li Peng Liu ◽  
Lan Cai
Keyword(s):  
Photonic Crystal ◽  
Femtosecond Laser ◽  
Detection System ◽  
Three Dimensional ◽  
Photon Absorption ◽  
Micro Fabrication ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Photo Polymerization ◽  
System A

The photo-polymerization induced by Two-Photon Absorption (TPA) is tightly confined in the focus because the efficiency of TPA is proportional to the square of intensity. Three-dimensional (3D) micro-fabrication can be achieved by controlling the movement of the focus. Based on this theory, a system for 3D-micro-fabrication with femtosecond laser is proposed. The system consists of a laser system, a microscope system, a real-time detection system and a 3D-movement system, etc. The precision of micro-machining reaches a level down to 700nm linewidth. The line width was inversely proportional to the fabrication speed, but proportional to laser power and NA. The experiment results were simulated, beam waist of 0.413μm and TPA cross section of 2×10-54cm4s was obtained. While we tried to optimize parameters, we also did some research about its applications. With TPA photo-polymerization by means of our experimental system, 3D photonic crystal of wood-pile structure twelve layers and photonic crystal fiber are manufactured. These results proved that the micro-fabrication system of TPA can not only obtain the resolution down to sub-micron level, but also realize real 3D micro-fabrication.

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