Experimental Studies of the Behaviour at High Strain Rates of Unfilled and Filled Polypropylenes

N. Temimi; Noelle Billon

doi:10.4028/www.scientific.net/AMM.3-4.363

Paper Titles

Measurement on Rotating Mechanical Component by Thermoelasticity
p.337

Evaluation of Rugged 'Smart Patch' Fibre-Optic Strain Sensors
p.343

On the Stiffness and the Reinforcement Effect of Electrical Resistance Strain Gauges
p.349

On the Feasibility of Thermoelastic Stress Analysis on Rapid Prototyping Models
p.355

Experimental Studies of the Behaviour at High Strain Rates of Unfilled and Filled Polypropylenes
p.363

Measurement and Analysis of Impact Test Data for X100 Pipeline Steel
p.369

Plastic Response of Nested Systems under Static and Dynamic Loading Conditions Using FE and Experimental Techniques
p.377

Behaviour of Multi-Layered Corrugated Paperboard Cushioning Systems under Impact Loads
p.383

Traceability of Optical Techniques for Strain Measurement
p.391

HomeApplied Mechanics and MaterialsApplied Mechanics and Materials Vols. 3-4Experimental Studies of the Behaviour at High...

Experimental Studies of the Behaviour at High Strain Rates of Unfilled and Filled Polypropylenes

Abstract:

Thermo mechanical behaviour of unfilled and filled polypropylenes are studied in tension from 10-4 to 102 s-1. Complementary low velocity compression and shear tests are also performed. A high-speed video camera (up to 2500 frames/s) combined with image analysis, image correlation and an infra red pyrometer allow measuring 3D-strain fields and temperature during tests. Thus, data can be processed without restrictive assumptions. Beside usual (for polymers) temperature and strain rate sensitivities it is found that plastic deformation in these materials does not obey incompressibility assumption. Voiding damage is evidenced in the polymer matrix by SEM observations that result in volume change and significant decrease in Young modulus for both materials. Moreover, an increase in the temperature of more than 10 °C is observed and is likely to modify the behaviour of each material at high strain rates. Shear and compression measurements demonstrate that yield criteria and constitutive equation depend on loading. It is concluded that apparent yield stress in semi-crystalline polypropylene can be a result of a combination of “non strain rate sensitive” “non-cohesive mechanisms” and “strain rate sensitive” “cohesive mechanisms”. Experimental characterisation on polymers should then be revisited as most of the usual assumptions are invalid and non monotonic tests should be generalized.