This thesis presents the theory and describes three interactive computer graphics programs for mechanical engineering design: Fatigue Analysis, Section Properties, and Beam Analysis. The Fatigue Analysis program sizes up a mechanical component, circular, rectangular, or any shape, to prevent fatigue failure. Six most generally accepted fatigue failure lines are available and any equivalent stress theories are allowed. It can also calculate the significant endurance limit with the theoretical stress concentration factor supplied by the user. The Section Properties program finds twenty section properties, such as area, area moment of inertia, and radius of gyration about different axis, of any shape plane cross section. The Beam Analysis program, using transfer matrix method, computes and also plots the curves of deflection, slope, moment, and shear along the beam. Static and forced, undamped dynamic analysis can be performed for beams of uniform or variable cross section. Uniformly or linearly varied distributed loads, concentrated point loads, applied moments, or combinations of all three may be applied. This program allows any combination of pinned, fixed, free, or guided flexural boundary conditions, even normally kinematically unstable condition can be handled if sufficient internal supports are provided. In-span support can be elastic springs and/or elastic moment spring. Modelling for dynamic response uses lumped mass. All three programs provide the option of using either English or SI units. The programming language used is BASIC and the micro-processor used is a Teketronix model 4051 with 32 K memory. / Master of Science