4. We want to investigate the failure properties of a glass fiber-reinforced epoxy composite with a...

Transcribed Image Text:

4. We want to investigate the failure properties of a glass fiber-reinforced epoxy composite with a 50% fiber volume fraction. The epoxy resin has a Young's modulus of Em = 3.1 GPa and an ultimate strength of m* = 50 MPa. The glass fibers have a Young's modulus of Ef = 68 GPa. The failure strength of the glass fibers can be well described by a Weibull distribution with m = 14.6 and 0- = 1125 MPa measured at a reference length of L = 60 mm. A unidirectional GFRP composite is made with a length L = 320mm and a uniaxial tension is applied along the fiber direction. a. Plot the percent chance of failure of the fibers as a function of the applied stress on the composite. At what applied stress would 1% of the fibers have failed? At what stress would 50% of the fibers have failed? Assume the stiffness of the composite doesn't change as fibers fail. (20 points) b. Which will fail first, the matrix or the fibers? What will the progression of failure be in the composite? Hint: first find the strain at which the matrix will fail assuming there is no fiber breakage. (10 points) 4. We want to investigate the failure properties of a glass fiber-reinforced epoxy composite with a 50% fiber volume fraction. The epoxy resin has a Young's modulus of Em = 3.1 GPa and an ultimate strength of m* = 50 MPa. The glass fibers have a Young's modulus of Ef = 68 GPa. The failure strength of the glass fibers can be well described by a Weibull distribution with m = 14.6 and 0- = 1125 MPa measured at a reference length of L = 60 mm. A unidirectional GFRP composite is made with a length L = 320mm and a uniaxial tension is applied along the fiber direction. a. Plot the percent chance of failure of the fibers as a function of the applied stress on the composite. At what applied stress would 1% of the fibers have failed? At what stress would 50% of the fibers have failed? Assume the stiffness of the composite doesn't change as fibers fail. (20 points) b. Which will fail first, the matrix or the fibers? What will the progression of failure be in the composite? Hint: first find the strain at which the matrix will fail assuming there is no fiber breakage. (10 points)