Finite-element analysis of softening effects in fissured, overconsolidated clays and mudstones

1991 ◽  
Vol 28 (1) ◽  
pp. 51-61 ◽  
Author(s):  
N. Yoshida ◽  
N. R. Morgenstern ◽  
D. H. Chan

The softening process as observed in fissured, overconsolidated clays and mudstones is discussed in detail. Softening is classified into internal and external processes. The effect of softening is to decrease the shear strength of a material and its dilatant characteristics. This shear strength reduction is represented as a lowering of the failure envelope and a reduction in the degree of nonlinearity at low stress levels. There are some restrictions related to stress paths that affect the initiation of softening. The softening process may be formulated in terms of a time-dependent yield surface, and the finite-element method can be extended to analyze softening effects. A cut slope is analyzed as an example. The development with time of deformations is traced up to the collapse of the slope. This example contains the essentials to portray the role of the mechanism of softening. A distinction can be made between time-dependent deformation due to softening and those associated with conventional creep mechanisms. Key words: softening, time-dependent strength reduction, finite-element analysis.

1998 ◽  
Vol 26 (2) ◽  
pp. 109-119 ◽  
Author(s):  
M. Koishi ◽  
K. Kabe ◽  
M. Shiratori

Abstract The finite element method has been used widely in tire engineering. Most tire simulations using the finite element method are static analyses, because tires are very complex nonlinear structures. Recently, transient phenomena have been studied with explicit finite element analysis codes. In this paper, the authors demonstrate the feasibility of tire cornering simulation using an explicit finite element code, PAM-SHOCK. First, we propose the cornering simulation using the explicit finite element analysis code. To demonstrate the efficiency of the proposed simulation, computed cornering forces for a 175SR14 tire are compared with experimental results from an MTS Flat-Trac Tire Test System. The computed cornering forces agree well with experimental results. After that, parametric studies are conducted by using the proposed simulation.


Author(s):  
Ashok K. Kancharala ◽  
Eric Freeman ◽  
Michael K. Philen

Biologically inspired droplet interface bilayers have found applications in the development of hair cell sensors and other mechanotransduction applications. In this research, the flexoelectric capability of the droplet bilayers under external excitation is explored for energy harvesting. Traditionally, membrane capacitance models are being used for inferring the magnitude of the membrane deflection which do not account for the relation between the applied force or deflection and the deflection of the interfacial membrane and time dependent variations. In this work, the dynamic behavior of the droplets under external excitation has been modeled using nonlinear finite element analysis. A flexoelectric model including mechanical, electrical, and chemical sensitivities has been developed and coupled with the calculated bilayer deformations to predict the mechanotransductive response of the droplets under excitation. Using the developed framework, the possibilities of energy harvesting for different droplet configurations have been investigated and reported.


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