Modeling of Rate-dependent Force-Displacement Behavior of MREs using Neural Networks for Torque Feedback Applications*

2020 ◽  
Author(s):  
Alireza Payami ◽  
Amir Hooshiar ◽  
Ali Alkhalaf ◽  
Javad Dargahi
Keyword(s):  
Neural Networks ◽  
Rate Dependent ◽  
Displacement Behavior ◽  
Force Displacement

Discrete-Direct Model Calibration and Uncertainty Propagation Method Confirmed on Multi-Parameter Plasticity Model Calibrated to Sparse Random Field Data

2021 ◽  
Vol 7 (2) ◽  
Author(s):  
Vicente J. Romero ◽  
Justin G. Winokur ◽  
George E. Orient ◽  
James F. Dempsey
Keyword(s):  
Strain Rate ◽  
Model Calibration ◽  
Structural Model ◽  
Uncertainty Propagation ◽  
Material Strength ◽  
Rate Dependent ◽  
Direct Model ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Force Displacement

Abstract A discrete direct (DD) model calibration and uncertainty propagation approach is explained and demonstrated on a 4-parameter Johnson-Cook (J-C) strain-rate dependent material strength model for an aluminum alloy. The methodology's performance is characterized in many trials involving four random realizations of strain-rate dependent material-test data curves per trial, drawn from a large synthetic population. The J-C model is calibrated to particular combinations of the data curves to obtain calibration parameter sets which are then propagated to “Can Crush” structural model predictions to produce samples of predicted response variability. These are processed with appropriate sparse-sample uncertainty quantification (UQ) methods to estimate various statistics of response with an appropriate level of conservatism. This is tested on 16 output quantities (von Mises stresses and equivalent plastic strains) and it is shown that important statistics of the true variabilities of the 16 quantities are bounded with a high success rate that is reasonably predictable and controllable. The DD approach has several advantages over other calibration-UQ approaches like Bayesian inference for capturing and utilizing the information obtained from typically small numbers of replicate experiments in model calibration situations—especially when sparse replicate functional data are involved like force–displacement curves from material tests. The DD methodology is straightforward and efficient for calibration and propagation problems involving aleatory and epistemic uncertainties in calibration experiments, models, and procedures.

Dynamic analysis of elastically and plastically graded spherical and cylindrical contact

2019 ◽  
Vol 233 (11) ◽  
pp. 1712-1728 ◽  
Author(s):  
Tamonash Jana ◽  
Anirban Mitra ◽  
Prasanta Sahoo
Keyword(s):  
Dynamic Analysis ◽  
Material Properties ◽  
Static Force ◽  
Contact Interface ◽  
Response Curves ◽  
Initial Displacement ◽  
Finite Element Software ◽  
Displacement Behavior ◽  
Force Displacement ◽  
Plastically Graded

A dynamic analysis of a hemispherical and cylindrical contact, material properties of which are graded elastically and plastically along the radius, is presented. The static force–displacement behavior of a hemisphere and a semi-cylinder in contact with a rigid flat is obtained using finite element software. The force–displacement is used in a further dynamic analysis for undamped-free as well as for forced-damped vibration of the contact interface. For the undamped free vibration, variation of natural frequency w.r.t. initial displacement is furnished for different values of elastic and plastic gradation parameter. In addition, variation of maximum initial displacement for contact loss is also demonstrated. The forced-damped vibration characteristics of the spherical and cylindrical contact interfaces are presented in the form of frequency response curves with jump up and jump down frequencies. Spherical and cylindrical contact interfaces are found to exhibit softening and hardening type nonlinearity, respectively.

Modeling Triple Friction Pendulum Bearings for Response-History Analysis

2008 ◽  
Vol 24 (4) ◽  
pp. 1011-1028 ◽  
Author(s):  
Daniel M. Fenz ◽  
Michael C. Constantinou
Keyword(s):  
Experimental Data ◽  
Equations Of Motion ◽  
Analysis Software ◽  
History Analysis ◽  
Response History Analysis ◽  
Displacement Behavior ◽  
Direct Numerical Integration ◽  
Friction Pendulum ◽  
Force Displacement ◽  
Comparison With Experimental Data

There are currently no applicable hysteresis rules or nonlinear elements available in structural analysis software that can be used to exactly model triple Friction Pendulum bearings for response-history analysis. Series models composed of existing nonlinear elements are proposed since they can be immediately implemented in currently available analysis software. However, the behavior of the triple Friction Pendulum bearing is not exactly that of a series arrangement of single concave Friction Pendulum bearings—though it is similar. This paper describes how to modify the input parameters of the series model in order to precisely retrace the true force-displacement behavior exhibited by this device. Recommendations are made for modeling in SAP2000 and are illustrated through analysis of a simple seismically isolated structure. The results are confirmed by (a) verifying the force-displacement behavior through comparison with experimental data and (b) verifying the analysis through comparison to the results obtained by direct numerical integration of the equations of motion.

scholarly journals Neurodegeneration exposes firing rate dependent effects on oscillation dynamics in computational neural networks

PLoS ONE ◽  
2020 ◽  
Vol 15 (9) ◽  
pp. e0234749 ◽  
Author(s):  
David Gabrieli ◽  
Samantha N. Schumm ◽  
Nicholas F. Vigilante ◽  
Brandon Parvesse ◽  
David F. Meaney
Keyword(s):  
Neural Networks ◽  
Firing Rate ◽  
Rate Dependent ◽  
Computational Neural Networks ◽  
Oscillation Dynamics

scholarly journals Dynamic axial crush response of circular cell honeycombs

2012 ◽  
Vol 468 (2146) ◽  
pp. 2981-3005 ◽  
Author(s):  
Royan J. D'Mello ◽  
Sophia Guntupalli ◽  
Lucas R. Hansen ◽  
Anthony M. Waas
Keyword(s):  
High Speed ◽  
Rate Dependent ◽  
Circular Cell ◽  
Axial Crush ◽  
Wide Range ◽  
Rate Effects ◽  
Constant State ◽  
Loading Methods ◽  
Fold Formation ◽  
Force Displacement

The dynamic axial crush response of circular cell polycarbonate honeycombs was studied for 3-cell and 7-cell specimens experimentally and through finite-element (FE) simulation. The experiments were conducted using two loading methods: (i) the wave loading device (WLD) method and (ii) the direct impact method (DIM). The specimens were subjected to crush velocities of about 12 000 mm s −1 in the WLD method and 5000 mm s −1 in the DIM. The two methods were used to obtain a fairly wide range of input velocities. The collapse sequence and displacement information of the specimens were captured using a high-speed camera. The mode of collapse was through progressive concertina-diamond fold formation over a fairly constant state of load, which is referred to as the crush load. The crushing was simulated using an explicit FE analysis using ABAQUS, with geometrically imperfect 3-cell and 7-cell honeycomb models that incorporated the rate-dependent properties of polycarbonate. The FE results were found to agree well with the experimental results in terms of overall force–displacement plots, thus providing a basis to extract energy absorption estimates from the models and to draw comparisons between the 3-cell and 7-cell response behaviour. Moreover, the dynamic crush results were compared against a quasi-static axial crush response to demonstrate the presence of rate effects.

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