I'm doing experiments with an elastomer and I'd like to know how I should determine tensile strength in practice. Is this the point where I begin to observe tears in the elastomer or where the material breaks into at least two pieces?
The setup I'm using involves a rectangular sample of the elastomer which is loaded vertically using increments of known mass. The elastomer has clamps applied at both extremities where it's fixed at one end and the load on the elastomer at any instant is known. It's assumed that breaking is nearly instantaneous (this is what has been observed from prior experiments) so the relevant dimensions for the cross-sectional area are assumed to be those prior to breaking.