Composites with Certain Material Testing Instruments

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Parameters To Consider For Tensile Test With Material Testing Instruments

You must know the fact about good tensile test to achieve optimum results. A good tensile test includes comprehensive measuring of composite material’s tensile strength and it is done with distinct material testing instruments. The testing requires a uniform distribution of axial stress across the composite test, or gage, section between the tabs. A tabbing configuration design is required for lowering the stress concentrations produced inside the tab termination region. While engineers can use several geometric and material parameters to design a tabbed tensile specimen for lowering the stress concentration, we bring top parameters that they should not ignore anyway!

Tab taper angle - You can taper the tab thickness to minimize the stress concentration. It may seem tempting to you, but the process has practical limits. Out-of-plane peel stresses developed at the tapered tab tip increase when the taper angle decreases, which results in failure of the adhesive bond.

Tab length - The minimum tab length relies to the load needed for specimen failure and the adhesive shear strength. When you raise the tab length, it will lower the stress concentration in the tab termination area. The whole un-tapered length of the tab needs to be gripped while testing in order to lower peel stresses at the termination point of the tab. This is why experts recommend using longest tab length with a minimum un-tapered 40 mm length.

Adhesive layer thickness - To reduce the stress concentration at the tab termination, you must use a thicker adhesive bond line as it is more complaint in contrast to tab and composite material. You can use Epoxy adhesives as they yield high strength in thicker bond lines.

Composite specimen thickness - Many times people ignore this parameter. You must decrease the composite specimen thickness to mitigate the discussed problem with tabbed tensile specimens.

You must consider these parameters while tensile testing of composites with certain material testing instruments. For expert assistance, call professionals who can perform the task efficiently and deliver expected results to you.