Effect of interfaces on continuous fiber-reinforced brittle matrix composites
The development of toughened brittle matrix composites (BMC) requires weak or non-existent chemical bonding at the fiber-matrix interface to improve longitudinal toughness. However, over-weakened bonding reduces the longitudinal strength of BMC. In this work, predictive models were developed to quantify the effect of modified interfaces on both transverse and longitudinal behavior of a unidirectional BMC lamina. Under transverse tensile loads, the experimentally measured strength and stiffness of a unidirectional BMC lamina have shown a dramatic decrease from that predicted by existing models. It was believed that weakened or debonded interfaces are responsible for the decrease in transverse mechanical properties. To support this claim, a two-dimensional finite element model of a transverse representative volume element was developed. Interface debonding was represented by active gap elements connecting the fiber and matrix. Using this model, the effects of fiber/matrix displacement compatibility at the interface on both transverse elastic properties and transverse strength were studied for tensile and compressive transverse loadings. The model results accurately predict the transverse strength and stiffness of a 30% SCS6/RBSN composite. Additionally, the results indicate that the transverse elastic properties of BMC are not linear-elastic. The longitudinal behavior of BMC was also modeled. From experimental evidence, subcritical composite failure under longitudinal loads begins as a transverse crack in the matrix with the fibers remaining intact.
- Research Organization:
- Pennsylvania State Univ., Middletown, PA (United States)
- OSTI ID:
- 5525614
- Country of Publication:
- United States
- Language:
- English
Similar Records
Modeling the mechanical behavior of brittle matrix composites using a finite element approach
The relationship between longitudinal stress and transverse strain during tensile testing of unidirectional fiber toughened ceramic matrix composites