Quantifying Time Dependent Viscoelastic Deformation during Coordinate Metrology Audits
Unmanaged viscoelastic creep under metrology clamping fixtures consumes up to forty percent of engineering tolerances, requiring documented dwell periods.
Viscoelastic Strain
Meaning
Deformation characteristics in polymers and biological tissues combine both viscous and elastic responses when subjected to external loading forces. A material experiencing viscoelastic strain does not return to its original shape instantly once the load is removed but shows a delayed recovery. It separates the immediate spring like reaction of a metal from the time dependent flow of a fluid.
This property governs how synthetic fibres and human skin respond to pressure.
Mechanical Response
Energy dissipation happens within the material as it deforms, turning mechanical work into heat. During viscoelastic strain, the relationship between stress and deformation changes depending on how fast the force is applied. A quick strike may cause a stiff reaction while a slow pull leads to more stretching.
Recovery Pattern
Hysteresis loops appear when the loading and unloading paths of the material are compared on a graph. With viscoelastic strain, the material takes a different path back to its resting state, indicating that some energy was lost during the cycle. This lag is a defining feature of dampers and shock absorbers.
Load Duration
Permanent changes in shape can occur if the pressure is maintained for too long. If viscoelastic strain is allowed to continue, the material may reach a point where it can no longer fully recover its dimensions. Engineers must calculate the exact timing of loads to ensure that components do not warp out of tolerance.