Non Isothermal Tube Model Characterization for High Speed Thermoforming Stretch
Accurate non isothermal tube characterization reduces thermoforming wall variance to under six percent at hundred hertz stretch rates.
Dynamic Orientation Tensor
Meaning
Mathematical representations of macromolecular alignment describe how polymer chains or fibers position themselves under the influence of shear forces. Calculating the dynamic orientation tensor during injection moulding simulation allows engineers to predict the anisotropic shrinkage of the final molded part. This calculation tracks the alignment in three dimensions at each transient step of the cavity filling process.
Moulding Simulation
Numerical models use the tensor components to evaluate how flow velocity profiles modify the fiber distribution through the thickness of the part. Applying the dynamic orientation tensor in transient flow equations solves the evolution of molecular directionality under varying shear and elongational rates. The resulting data help designers position gates to avoid warpage zones caused by unbalanced material orientation, which often arises in complex geometries with thin walls where the flow front changes direction rapidly.
By analyzing the transient changes, engineers can alter the process variables to achieve a more uniform distribution.
Anisotropic Shrinkage
Differential cooling and localized shrinkage of the molded part occur when the molecular chains align preferentially in one direction. High values in the dynamic orientation tensor indicate that the part will shrink more across the flow direction than along it. Moulders must adjust injection speeds to minimize this direction-dependent variation.
Prediction Accuracy
Comparing calculated alignment patterns with actual part performance verifies the reliability of the flow simulation. Inaccurate predictions of the dynamic orientation tensor lead to out-of-tolerance parts and expensive tooling modifications. Ensuring correct melt temperature inputs in the software is necessary to achieve matching physical and simulated results.