On the Initial Speed of Elastic-Plastic Boundaries in Longitudinal Wave Propagation in a Rod

1971 ◽  
Vol 38 (2) ◽  
pp. 441-447 ◽  
Author(s):  
T. C. T. Ting

A study is given of elastic-plastic boundaries which start at the end x = 0 of a rod in one-dimensional wave propagation. The initial speed of the elastic-plastic boundaries at x = 0 and at any time, say t = t0, is determined analytically for all possible combinations of the time derivative σt of the stress σ(0, t) before and after t = t0. If σt at x = 0 is continuous and vanishes at t = t0, all possible combinations of σtt before and after t = t0 are considered. The analysis also gives the number of regions involved, the derivatives in each region, and distinguishes elastic regions from plastic regions. These are useful guides for a numerical solution of general initial and boundary-value problems.

1968 ◽  
Vol 35 (4) ◽  
pp. 782-786 ◽  
Author(s):  
R. J. Clifton

Assuming a one-dimensional rate independent theory of combined longitudinal and torsional plastic wave propagation in a thin-walled tube, restrictions are obtained on the possible speeds of elastic-plastic boundaries. These restrictions are shown to depend on the type of discontinuity at the boundary and on whether loading or unloading is occurring. The range of unloading (loading) wave speeds for the case when the nth time derivative of the solution is the first derivative that is discontinuous across the boundary is the complement of the range of unloading (loading) wave speeds for the case when the first discontinuity is in the (n + 1)th time derivative. Thus all speeds are possible for elastic-plastic boundaries corresponding to either loading or unloading. The general features of the discontinuities associated with loading and unloading boundaries are established, and examples are presented of unloading boundaries overtaking simple waves.


1968 ◽  
Vol 35 (4) ◽  
pp. 812-814 ◽  
Author(s):  
R. J. Clifton ◽  
T. C. T. Ting

1971 ◽  
Vol 93 (4) ◽  
pp. 478-480 ◽  
Author(s):  
J. G. Wagner

Bounds are established on the errors associated with elastic-plastic strain wave measurements involving finite gage lengths. Attention is restricted to the case of one-dimensional wave propagation in a semi-infinite bar. A bi-linear model of the stress-strain behavior provides a means of calculating realistic upper and lower bounds on the relative error of amplitude measurements. Rise time errors are also discussed and illustrated.


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