Meaning
Measurement of physical movement or deformation without direct mechanical contact utilizes optical, laser or ultrasonic sensors to monitor a specimen. In the testing of soft polymers and heated plastic sheets, non-contact displacement measurement prevents the localized stresses and cooling that occur with physical attachment probes.
Strain Measurement
Extensometers that clip directly onto polymer specimens can cause premature failure at the contact points. Implementing non-contact displacement tracking via optical methods avoids this issue, ensuring that the specimen deforms naturally. This yields highly accurate tensile data, particularly for fragile or highly elastic elastomers.
Eliminating mechanical contact allows for uninterrupted tracking of high-strain deformations up to the point of rupture, providing a complete stress-strain curve for polymer characterization.
Process Monitoring
Molten polymer extrudates and hot sheets are highly sensitive to physical disruption during deformation. Using non-contact displacement sensors allows for real-time tracking of sheet sag and draw ratios on the production floor. This data enables immediate adjustment of process parameters to prevent thinning or tearing during forming operations.
Calibration Quality
Advanced simulation models require highly accurate strain data to predict polymer behavior. Data gathered using non-contact displacement methods are used to calibrate hyperelastic and viscoelastic material models. This ensures that the simulations of processes like stretch blow moulding are based on realistic deformation profiles.
