Materials Behavior and Processing — Lab Reports

Experimental characterization of Aluminum 2024-T3 and Brass 360 through three complementary mechanical tests. Tensile dog-bone specimens were loaded to failure on a load frame with PASCO Capstone data acquisition, producing full stress-strain curves from which elastic modulus, 0.2% offset yield strength, ultimate tensile strength, percent elongation, and work of fracture were extracted. Shear testing provided shear strength values and the shear-to-tensile ratio. Vickers hardness indentation (with optical microscope measurement of indent diagonals) yielded estimated hardness numbers (HV) and yield strength approximations for both materials. Results showed aluminum had higher yield and ultimate strength, while brass demonstrated greater hardness and resistance to permanent deformation.

Investigation of how work hardening and annealing alter the mechanical properties of Brass 360 and Steel 1018. Brass bar stock was cold-worked on a rolling mill at 2, 4, and 6 turns, with percent reduction and true strain calculated at each step. Vickers hardness tests (300 gf, optical micrometer measurement) were performed on as-received, cold-worked, and annealed brass samples to track yield strength evolution. Results confirmed increasing yield strength with cold-working due to dislocation density buildup, and strength recovery following annealing at 500 °C. Two 1018 steel dog-bone specimens — one cold-worked, one fully annealed — were tensile tested to failure, producing stress-strain curves that quantified the reduction in strength and increase in ductility from the annealing process.

End-to-end manufacturing and mechanical testing of five polymer matrix composite beam specimens: one neat epoxy resin control, two reinforced with 8 layers of woven continuous fiberglass fabric, and two with randomly distributed chopped glass fibers. Samples were hand laid up in a 5-cavity mold, cured, and sanded to ~9×9×50 mm rectangular prisms. Three-point bend testing was performed on a load frame (PASCO Capstone), yielding full force-displacement curves for each sample. Flexural modulus and bending strength were calculated using beam theory. Continuous fiber sample 3 achieved the highest flexural strength at 148.1 MPa; chopped fiber sample 4 achieved the highest flexural modulus at 6.156 GPa. Failure modes — brittle fracture (neat resin) vs. gradual ductile failure (fiber-reinforced) — were documented and discussed.