Abstract
The double torsion (DT) technique has proved its usefulness in fracture mechanical testing. Practical considerations make it preferable to other methods in many cases. Nevertheless, it is sometimes considered with reluctance, first because of its curved crack front and secondly because of a misunderstanding of the related problems. Experiments were conducted on polymethylmethacrylate (PMMA) to elucidate the effect of crack velocity and geometry. It was found that the crack front profile does not vary with crack velocity, whereas the geometry of the specimen has a strong influence on it. A simple model is developed, based on a strain fracture criterion. It describes quite well the experimental profiles of PMMA. Crack opening displacement, shear modulus, stress intensity factor and Poisson's ratio are shown to be of importance. The influence of the subcritical crack growth exponent could be effective for some materials but not for PMMA.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
