Discussion of the Load-Elongation Curves in Tensile Testing

1 Discussion of the Load-Elongation Curves in Tensile Testing 

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Discussion of the load-elongation curves in tensile testing... 

DISCUSSION OF THE LOAD ELONGATION CURVES IN TENSILE TESTING... 

Yield stress may be regarded most simply as the minimum stress at which permanent strain is produced when the stress is subsequently removed. Although this deformation is satisfactory for metals, where there is a clear distinction between elastic recoverable definition and plastic irrecoverable deformation, in polymers the distinction is not so straightforward. In many cases, such as the tensile tests discussed above, yield coincides with the observation of a maximum load in the load-elongation curve. The yield stress then can be defined as the true stress at the maximum observed load (Figure 11.8(a)). Because this stress is achieved at a comparatively low elongation of the sample, it is often adequate to use the engineering definition of the yield stress as the maximum observed load divided by the initial cross-sectional area. 

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