Stronger, lightweight materials exhibiting fail-safe failure modes are becoming a necessity amidst concerns of dwindling energy sources, and rising pollution levels. The requirement for stronger and lighter materials has given rise to the implementation of fiber reinforced polymers (FRP) used in conjunction with metals. Bonding of composite materials to metals is challenging. One of the ways to improve the bonding is to use penetrative reinforcements, instead of chemical treatment. The processes required to produce such modified surfaces is costly for full-scale implementation. The use of a cold working to form penetrative reinforcements provides an environmentally friendly method. The investigation of the properties of this technology employed on a single shear lap joint is investigated to determine ultimate strength, fatigue performance, impact fatigue, and finally failure modes under different surface configurations. Use of a novel tumbling method to test impact fatigue is developed and test results are reported.