The mechanical performance of injection-molded short glass-fiber-reinforced thermoplastic components is anisotropic and is highly dependent on the fiber-orientation and distribution. Similarly, the bulk and short and long-term mechanical performance at the weld is influenced by these fibers and the specific welding technology used as related to melt-pool formation. The purpose of this analysis is to show: 1. the short-fiber-orientation (analytical and simulation data) and distribution at the prewelded bead, ribs, and wall areas; 2. advantages of SigmaSoft injection-molding simulation software, which utilizes full threedimensional fiber representation of any molded part; 3. the mechanical performance of welds with optimized geometry (US Patent 6,447,866). Findings on the mechanical performance of butt-joints with different designs and localized geometry will help designers and technicians with plastic part design optimization. In a previous ANTEC paper (Part I) (Kagan, V.A. and Roth, C. (2002). The Effects of Weld Geometry and Glass-Fiber Orientation on the Mechanical Performance of Joints - Part I: Kinetics of Glass-fiber-orientation and Performance at Bulk and Weld Areas, Design Issues, In: ANTEC Proceedings), we related these findings to the kinetics of welds and part design issues for straight and T-type butt-joints.