Crack Propagation in a Linearly Viscoelastic Strip

Abstract

The tip velocity of a crack propagating through a viscoelastic material depends on geometry, applied load and its history, and material properties. A consideration of the work done by the unloading tractions at the crack tip shows that, for a large crack propagating through an infinitely long strip under constant lateral strain, the rate of propagation can be calculated from a knowledge of the intrinsic fracture energy (a material constant), the material creep compliance, and an additional size parameter. This parameter vanishes from the analysis if the material is elastic, and the familiar instability criterion is obtained in this case. Comparison with experimental data is provided and the consequences of step loadings are examined.

Stress-intensity factor and crack opening for a linearly viscoelastic strip with a slowly propagating central crack

“…The very tip of the crack, however, remains blunt but has a radius of curvature which is several orders of magnitude smaller than that of the stationary crack [13].…”

“…'n) (x, 0) cannot be evaluated in closed form. An investigation [13] of their properties, however, shows that for x -a the s t r e s s is given by…”

“…and using integration by parts it can be shown [13] that there is one dominating t e r m as x -a and a simplified expression for the opening near the propagating crack tip can be derived where use has been made of ( 2 9 ) and the new independent variable Figure 6 shows the shape of the crack tip a s a function of crack velocity for a particular composition of the Polyurethane elastomer Solithane 113 [16] , perature is about 1. 0 min.…”

Fracture Mechanics and the Time Dependent Strength of Adhesive Joints

“…The latter determination is irnportant because it combines the effect of loading and geometry to determine whether the crack accelerates [ S. 151 or propagates at a steady. possibly slow speed [ 13 ].…”

Crack Propagation in Double-Base Propellants

“…Knauss (5,8) developed an approximate solution for a line crack problem which incorporates a failure zone length to introduce time and velocity effects. Knauss and Mueller (5,6) applied the theory to an unfilled polyurethane polymer with encouraging results achieved for a variety of loading environments.…”