A Simple Dynamic Model for Beams Subjected to Blast Loads

2012 ◽  
Vol 479-481 ◽  
pp. 1763-1767
Author(s):  
Z.N. Yin
Keyword(s):  
Dynamic Response ◽  
Deformation Behavior ◽  
Spring Model ◽  
Blast Loads ◽  
Lumped Mass ◽  
Proposed Model ◽  
Mass Spring Model ◽  
Three Degree Of Freedom ◽  
Mass Spring ◽  
The Relationship

A three Degree-of-Freedom (DoF) mass-spring model is proposed to predict the dynamic response of clamped supported beams subjected to blast loads at the mid-span of the beam. The stiffness of inelastic spring is defined from the relationship between force and mid-span displacement of beams subjected to blast loads. The lumped mass is calculated from the equivalency between the model and beam based on the fundamental frequency. Clamped supported solid beams and T-beams are taken as typical examples to verify the proposed model. And the influence of geometric parameters on deformation behavior is discussed in details.

Stability and Bifurcation Analysis of an Asymmetrically Electrostatically Actuated Microbeam

2015 ◽  
Vol 10 (2) ◽  
Author(s):  
Hadi Madinei ◽  
Ghader Rezazadeh ◽  
Saber Azizi
Keyword(s):  
Applied Voltage ◽  
Equilibrium Points ◽  
Pitchfork Bifurcation ◽  
Spring Model ◽  
Electrostatically Actuated ◽  
Proposed Model ◽  
Mass Spring Model ◽  
The Stability ◽  
Mass Spring ◽  
Two Degree Of Freedom

This paper deals with the study of bifurcational behavior of a capacitive microbeam actuated by asymmetrically located electrodes in the upper and lower sides of the microbeam. A distributed and a modified two degree of freedom (DOF) mass–spring model have been implemented for the analysis of the microbeam behavior. Fixed or equilibrium points of the microbeam have been obtained and have been shown that with variation of the applied voltage as a control parameter the number of equilibrium points is changed. The stability of the fixed points has been investigated by Jacobian matrix of system in the two DOF mass–spring model. Pull-in or critical values of the applied voltage leading to qualitative changes in the microbeam behavior have been obtained and has been shown that the proposed model has a tendency to a static instability by undergoing a pitchfork bifurcation whereas classic capacitive microbeams cease to have stability by undergoing to a saddle node bifurcation.

Deformation Analysis of a Compliant Underactuated Finger Grasping a Soft Object

2018 ◽  
Author(s):  
Nicolas Mouazé ◽  
Lionel Birglen
Keyword(s):  
Deformation Analysis ◽  
Spring Model ◽  
Rigid Objects ◽  
Proposed Model ◽  
Mass Spring Model ◽  
Soft Objects ◽  
Simple Mass ◽  
Computationally Intensive ◽  
Mass Spring ◽  
Soft Object

In the literature, many models of compliant fingers grasping rigid objects have been extensively discussed. However, when the objects are themselves deformable, as in many practical cases, the effect of compliant underactuated fingers onto these soft objects is generally not addressed due to the complexity of the model required for accurate results. This paper aims at addressing this issue by proposing to simulate deformations using a simple mass-spring model. This model discretizes the object similarly to how a pseudo-rigid body technique usually approximates the compliant finger. Comparisons between simulations using the proposed model and finite element analyses demonstrate that for a significant range of deformations our approach offers an efficient and accurate approximation while less computationally intensive.

An improved dynamic modeling approach of aerostatic thrust bearing considering frequency-varying stiffness and damping of air film

2021 ◽  
pp. 1-42
Author(s):  
Hui Zhuang ◽  
Jianguo Ding ◽  
Peng Chen ◽  
Yu Chang ◽  
Xiaoyun Zeng ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Dynamic Modeling ◽  
Vibration Analysis ◽  
Thrust Bearing ◽  
Spring Model ◽  
Modeling Approach ◽  
Mass Spring Model ◽  
Mass Spring ◽  
Stiffness And Damping ◽  
Air Film

Abstract The damped mass-spring model is often employed for the dynamic modeling and vibration analysis of aerostatic bearing systems by taking the air film as equivalent springs. However, the stiffness and damping of the air film are frequency-dependent, making the commonly used approach of taking static stiffness or fixed value as the spring coefficient no longer applicable for a bearing subject to a complex external force containing different frequencies. To address this issue, this paper develops the damped mass-spring model for the aerostatic thrust bearing considering the frequency-varying stiffness and damping by means of the linear superposition method. It indicates that the air bearing is still a linear system despite the frequency-dependent character of dynamic coefficients because the bearing vibration satisfies the superposition principle. The improved dynamic modeling approach is able to accurately and efficiently predict the overall dynamic response of the thrust plate when the it is subjected to a multi-frequency vibration. In solving the overall dynamic response, the stiffness and damping associated with the responses of the transient part and steady part correspond to the natural vibration frequency and external disturbance frequencies, respectively. The feasibility and accuracy of the improved modeling approach are partly or completely verified by the direct trajectory calculation method, the CFD dynamic mesh simulation and a modal test. The proposed modeling method provides an effective way for the vibration analysis of air bearings, and in the meantime avoids the possible numerical errors caused by the traditional modeling approach.

scholarly journals A Calculation Method for the Deformation Behavior of Warp-Knitted Fabric

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Haisang Liu ◽  
Gaoming Jiang ◽  
Zhijia Dong ◽  
Shuai Jin
Keyword(s):  
Deformation Behavior ◽  
Structural Characteristics ◽  
Loop Model ◽  
Control Points ◽  
Spring Model ◽  
Mass Spring Model ◽  
Fabric Deformation ◽  
Warp Knitted Fabric ◽  
Simulator Program ◽  
Mass Spring

Abstract In this paper, a new method to simulate the structure and loop deformation behavior of double-bar reflex-lapping warp-knitted fabrics based on the structural characteristics is proposed. A simplified mass-spring model was built in which loops knitted by filaments were considered as particles with the uniform mass distribution connected by structure springs for overlaps and shear springs for underlaps. Deformation forces and direction on particles were analyzed to describe the displacement and deformation behavior of particles. A loop model with eight control points was established, and the relationship between control points and particles was studied combining the quadratic Bezier curves. The deformation simulation was implemented by a simulator program with C# and JavaScript via web technology on Visual Studio 2015. The stereoscopic sense of filaments was realized by changing the direction and intensity of the light. The results show that the fabric deformation and the loop shape can be accurately achieve using the simplified mass-spring model compared with the real sample.

One-Dimensional Analysis on the Dynamic Response of Cellular Chains to Pulse Loading

2006 ◽  
Vol 220 (5) ◽  
pp. 679-689 ◽  
Author(s):  
Z. Y. Gao ◽  
T. X. Yu
Keyword(s):  
Dynamic Response ◽  
Elastic Wave ◽  
Deformation Characteristic ◽  
Cell Number ◽  
Pulse Loading ◽  
Plastic Collapse ◽  
Spring Model ◽  
One Dimensional ◽  
Mass Spring Model ◽  
Mass Spring

On the basis of our previous studies of a typical type II structure (i.e. a pair of prebent plates), a simplified one-dimensional mass-spring model is proposed to describe the uniaxial load-deformation characteristic of cellular materials and structures. When compared with the previous mass-spring model proposed by Shim et al., the present model employs fewer parameters (only two) to describe elastic-plastic behaviour, and the structural hardening/softening is represented by only one of the parameters. The model is then used to study the dynamic response of a cellular chain to a pulse loading of specified force intensity and duration. By adjusting the value of a single parameter adopted in the model, each cell of the cellular chain is identically assigned to possess either an elastic-hardening or an elastic-softening-consolidation property. The effects of material elasticity, cell compliance characteristic, cell number, and pulse intensity and duration are all examined by this model and discussed in detail. A special attention is paid to the initiation and propagation of the plastic collapse of the cells in the cellular chain so as to identify the governing parameters. Apart from the elastic wave speed, two other characteristic velocities, i.e. the particle velocity induced by the elastic wave and the plastic collapse propagation velocity, are defined and analytically evaluated. It is found that these three characteristic velocities completely govern the elastic and plastic dynamic behaviour of the cellular chains.

Structural deformation behavior of Jacquardtronic lace based on the mass-spring model

2016 ◽  
Vol 87 (10) ◽  
pp. 1242-1250 ◽  
Author(s):  
Xinxin Li ◽  
Aijun Zhang ◽  
Pibo Ma ◽  
Honglian Cong ◽  
Gaoming Jiang
Keyword(s):  
Deformation Behavior ◽  
Euler Method ◽  
Structural Deformation ◽  
Spring Model ◽  
Yarn Tension ◽  
Detection Model ◽  
Motion State ◽  
Mass Spring Model ◽  
Simulator Program ◽  
Mass Spring

To simulate the structural deformation behavior of Jacquardtronic lace, which is formed on a multibar Jacquard Raschel machine and is widely used in female fashion, the key influencing factors on structural deformation were introduced and a tailored mass-spring model was built in which the lace was considered to be numbers of evenly distributed particles connected by elastane springs. These springs covered structural springs, restriction springs and spiral springs, respectively, created for ground pillars, Jacquard inlays, pattern lapping and elastane yarns. The elastane force on particles was analyzed to study motion state and deformation behavior with the explicit Euler method. The deformation simulated models were implemented by a simulator program via Visual C++ and were tested with a lace sample. Particular attention was paid to analyzing the effect of Jacquard structures and yarn tension on deformation and the detection model was introduced to avoid improper deformation caused by excessive yarn tension. The simulation results showed practicability and efficiency when compared with the real sample.

scholarly journals Review on the 3-D simulation for weft knitted fabric

2021 ◽  
Vol 16 ◽  
pp. 155892502110125
Author(s):  
Sha Sha ◽  
Anqi Geng ◽  
Yuqin Gao ◽  
Bin Li ◽  
Xuewei Jiang ◽  
...  
Keyword(s):  
Physical Models ◽  
Spring Model ◽  
Finite Element Analyses ◽  
Knitted Fabrics ◽  
Piecewise Function ◽  
Fabric Structure ◽  
Weft Knitted Fabric ◽  
Mass Spring Model ◽  
Virtual Display ◽  
Mass Spring

There are different kinds of geometrical models and physical models used to simulate weft knitted fabrics nowadays, such as loop models based on Pierce, piecewise function, spline curve, mass-spring model, and finite element analyses (FEA). Weft knitting simulation technology, including modeling and yarn reality, has been widely adopted in fabric structure designing for the manufacturer. The technology has great potentials in both industries and dynamic virtual display. The present article is aimed to review the current development of 3-D simulation technique for weft knitted fabrics.

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