Phase I
During Phase I, experimental tests at room temperature were performed under compression, tension, and impact loading. A material database was established to characterize the time-dependence and the strain to failure for the thermoplastic polycarbonate (PC). An ISV Material Model (MSU model) was evaluated. A fitting routine was established and the model prediction was validated through various tests available in compression, tension, and impact. The MSU model showed its ability to predict the mechanical behavior in compression and tension at 25˚C under various strain rates. Regarding the impact tests, the failure strain obtained from numerical analysis using the MSU model was in good agreement with the impact test results and the data available from prior publications for PC.
GOALS:
1) Perform compressive, tensile, and impact tests at three loading rates at room temperature for polycarbonate (PC).
2) Perform model correlation on the available tension and compression data with loading rate dependencies.
3) Predict and validate the material models on an impact disk for PC.
FINAL REPORT (download link)
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Phase II
For Phase II, experimental tests were performed under compression, tension, impact, and three-point bend loading at different strain rates and temperatures for two different thermoplastics: an amorphous polycarbonate (PC) and a semicrystalline polypropylene (PP). A material database was established to capture the time, temperature, and stress state dependencies, as well as failure mechanisms and large-strain mechanical responses of PC and PP. The ISV-based MSU model was improved from Phase I, and the model’s predictions were validated for PC and PP through various tests available at different strain rates and temperatures. The MSU model showed its ability to predict the mechanical behavior of PC and PP in compression, tension, impact and three-point bending tests. Failure criteria, based on the maximum principal stress and equivalent plastic strain, were investigated with mixed results to predict the brittle and ductile failure of PC.
GOALS:
1) Enhance the material database from Phase I by including compression, tension, impact, and three point bending test data performed at different strain rates and temperatures for two different thermoplastics: an amorphous polycarbonate (PC) and a semicrystalline polypropylene (PP).
2) Improve the MSU material model for thermoplastics (developed in Phase I) by accounting for the temperature dependence of thermoplastics.
3) Perform model correlation on the available tension and compression data with loading rate and temperature dependencies for PC and PP.
4) Predict and validate the material model on impact disk and three point bending tests and compare with the failure criteria available in the TED Calculator [Woods and Trantina, 1998] for brittle and ductile failure.
FINAL REPORT (download link)
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Phase III
In continuation of the work began in Phase I and II, Phase III continues the development of a structure-property relationship database for selected polymeric materials along with a constitutive framework which captures the material response and failure of the polymers. This phase focused on studying a copolymer polypropylene (co-PP). Compression, tension, impact, and three point bend tests were performed on the co-PP to capture the time, temperature, and stress state dependence of co-PP. The ISV-based MSU model developed during Phase I and II was applied, and fitting routines were used to calibrate the material parameters. The model’s predictions for co-PP were validated through various tests available at different strain rates and temperatures. Failure criteria, obtained from numerical analysis, were applied to predict the brittle or ductile failure of co-PP in the three-point bending tests.
GOALS:
1) Enhance the material database developed in the previous contract by including compression, tension, impact, and three point bending test data performed at different strain rates and temperatures for a copolymer polypropylene (co-PP). (link to test matrix)
2) Improve the MSU material model (developed in previous contract) for PP material.
3) Perform model correlation on the available tension and compression data with loading rate and temperature dependencies for co-PP.
4) Predict and validate the material model on impact disk and three-point bending tests and for co-PP.
FINAL REPORT (download link)
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