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A state of the art proprietary method for aluminum-to-aluminum joining in the automotive industry is Resistance Spot Welding. However, with spot welding (1) structural performance of the joint may be degraded through heat-affected zones created by the high temperature thermal joining process, (2) achieving the double-sided access necessary for the spot welding electrodes may limit design flexibility, and (3) variability with welds leads to production inconsistencies. Self-piercing rivets have been used before; however they require different rivet/die combinations depending on the material being joined, which adds to process complexity. In recent years the introductions of screw products that combine the technologies of friction drilling and thread forming have entered the market. These types of screw products do not have these access limitations as through-part connections are formed by one-sided access using a thermo-mechanical flow screwdriving process with minimal heat.

To warrant the substitution of traditionally used structural automotive materials with titanium alloys, the material substitutional and redesign advantages must be attainable at a justifiable cost. Typically, during material replacement with such ‘exotic’ aerospace alloys, the initial raw material cost is high; therefore, cost justification will need to be realized from a life-cycle cost standpoint. Part I of this paper highlighted the redesign, fabrication, and validation of an automotive component. Part II details the particulars of constructing the total life-cycle cost model for both prototypes (P1, P2). Considerations in the model include adaptation to a high volume production scenario, availability of near-net size plate/bar stock, etc. Further, response surfaces of fuel costs savings and consequent life-cycle costs (state-variables) are generated against life-cycle duration and unit fuel price (design-variables) to identify profitable operating conditions.

Current vehicle manufacturers must meet economic demands and design/manufacture more fuel efficient vehicles with increasingly better performance. As a result, they are turning to the use of more non-traditional lightweight materials in their products. One favorable material due to its excellent strength-to-weight ratio and high corrosion resistance is titanium. However, to warrant the replacement of traditional materials with titanium alloys there must be the benefit of reduced vehicle mass as well as performance enhancement gains from the substitution at a justifiable cost. In this work, an unsprung suspension component is selected and redesigned from the standpoint of (i) a direct material substitution and (ii) a material and requirements consideration based substitution. In addition, for the redesign of the component in titanium, the manufacturing procedure and process plan is integrated into the design phase for the component.