Innovative Interlaminar Mode I and Mode II Fracture Toughness Test Methods for Ceramic Matrix Composites
Ceramic Matrix Composites (CMCs) are prone to interlaminar failure due to poor interlaminar properties. In spite of this importance, there are very few standardized tests dedicated to measuring these important properties. MR&D’s role as an industry leader in providing design/analysis services for the advanced materials community provides the expertise to develop such test standards, including fracture toughness. The new standardized testing method will have a direct effect on numerous applications seeking to incorporate CMC materials. Such a solution will give confidence to the quantitative evaluation of crack propagation and the criticality of defects for a given component so needless part replacement can be minimized. To reduce acceptance risks, MR&D is validating these methods on a variety of CMC materials ranging from high to low toughness.
Ultra Sharp Fiber Architectures for Ceramic Composites
Hypersonic aerodynamic efficiency and performance is currently constrained by materials capabilities. Airframes and control surfaces with sharp leading edges offer improved velocity and range by reducing drag but at the cost of higher temperatures and stresses. While ceramic composites offer thermochemical stability and strength; the diminutive scale of sharp leading edges precludes the use of traditional reinforcements. Materials Research & Design (MR&D), through our design/analysis services and partners, has developed a high-temperature ceramic composite material for erosion free leading edge applications. MR&D uses fine diameter tungsten wire reinforcements to produce a small scale composite that can be manufactured into ultra-sharp geometries. MR&D and its partners ultimately seek to demonstrate the fabrication of an ultra-sharp ceramic composite utilizing very fine tungsten wires and to prove its effectiveness in ground based arc jet testing.
Aircraft and other aviation components have contours for aerodynamic performance using composite sandwich structures for high strength-to-weight ratio. MR&D is exploring these complex sandwich structures through the development of a multi-scale material model tailored for the design of pin-reinforced foam cores capable of near net shape fabrication to meet critical performance needs. MR&D’s role as an industry leader in providing design/analysis services for the advanced materials community provides the necessary experience to develop such a complex material model. Future vertical lift aircraft are expected to be the immediate beneficiaries of such a development. Such a solution will greatly improve the development of pin-reinforced foam cores capable of achieving strength-to-weight ratios not capable with heritage solutions. To reduce risks, MR&D is validating the model with a variety of fabrication and experimental tasks.