Historical BIW Development
In the first phase of the hydroform intensive body structure (HIBS) studies, simple hydroform assemblies were substituted for conventional stamped body structures to understand cost and mass implications. In Phase II, the hydroform designs took advantage of the latest material offerings, such as boron and variable-thickness tubes, and one-sided welding in the body shop as options for additional mass savings. Both studies demonstrated solid improvements over traditional stamped designs.
In HIBS Phase III, the intent is to take a closer look at how hydroformed tubes achieve their structural efficiency over stampings. Recent applications of hydroformed tubes in new vehicles will reinforce the hypothesis that hydroform tubes are an excellent choice for primary vehicle structures.
The results of the HIBS I study highlighted good mass and cost saving potential as shown here.
In HIBS II the front end, body side and rear floor structures were evaluated individually for the effects of higher strength steels, variable-thickness tubes and allowing one sided welding in the body shop (for manufacturing flexibility). Compared to HIBS I, additional savings were realized in each of the areas of the vehicle, and for each of the design assumptions. For example, Figure 1 shown here summarizes the outcomes for the rear rail study.