Stress-Strain Behaviour

The stress-strain properties of an adhesive can be measured from bulk samples in tension, shear or compression and from joints in shear. The properties are affected by the absorption of atmospheric moisture resulting in a reduction in the glass transition temperature (Tg). For adhesives where Tg is above the operating temperature, moisture reduces the yield stress, increases ductility and increases creep rates.

Stress-strain properties can be used to define model parameters for input to finite element analysis.

The graph opposite shows how % mass uptake of moisture affects the stress-strain behaviour of the adhesive, lowering both the Young's modulus and yield stress.