Residual Stress Effects Upon SIF Distribution for Cracks Parallel to and Within Bond Lines in Rubberlike Materials
Abstract
As a result of the need to extend the storage life of rocket motors, new emphasis has been placed upon the effect of cracks developed during storage and transport on the integrity of motor performance, In addressing this need, the authors have developed a three specimen test procedure for evaluating the stress intensity factor (SIF) distribution for cracks through the thickness of rubberlike materials near to and within simulated bond lines between the motor grain and its liner. A refined frozen stress method is employed for making measurements, and preliminary studies have shown that, for cracks in the bond line under both Mode I and Mixed Mode loads, the stress intensity factors are elevated primarily due to bond line residual stresses and may not be affected by modulus mismatch. In the present study, the refined frozen stress method is applied with the three specimen technique to edge cracks which are both parallel to and within the bond line. Since the three specimen method utilizes both homogeneous bonded and bimaterial bonded specimens, the bond line effect is separated from modulus mismatch effects. Results of the study show that cracks parallel to the bond line develop both an elevated Mode I SIF and a shear mode as they are placed closer to the bond line. These effects are shown to be due to critical temperature (T(sub c)) mismatch. Cracks in the bond line exhibit a somewhat elevated SIF but no shear mode. The SIF elevation is mainly due to residual bond line stress and modulus mismatch is shown to have virtually no effect.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 10, 1998
- Accession Number
- ADA397970
Entities
People
- C. W. Smith
- Chun Ting Liu
- E. F. Finlayson
Organizations
- Air Force Research Laboratory