113 12.5 Structural Behavior 12.5.1 Structural Behavior Samples Samples of rotational equipment were prototyped and loaded into drivetrain assemblies to test duty cycles to failure. The metal-to-composite interfaces had machnical interlocks, and were attached by overmolding in some parts, interference-fit in some parts, and adhesive bonding in some parts. The rotational components were tested for noise, torsional strength, and fatigue life in dynamometers. The rotational parts were made of metal components and composite components. The composite components were attached to the metal by van der Waals forces (overmolding), friction (interference fit), and by covalent bonds (two-component adhesive bonding), depending on how these were assembled. All were built to current standards for such equipment, and tested in existing housings that are readily available in the marketplace. 12.5.2 Structural Behavior Verification The components were prototyped to full scale, assembled into a drivetrain subassembly, and mounted on dynamometers that were customized to perform the duty cycles of vehicles, in a stationary test cell. For the rotational components that were overmolded, as reinforced thermoplastic on textured metal, the parts failed after conventional all-metal subassembly components failed and were replaced, but before the duty cycle was completed, for verification testing. The metal-and-composite rotational part assembled by overmolding failed just before achieving 20 % of the duty cycle, where the baseline is an all-cast-iron part that achieves five-times more cycling to failure. This metal-and-composite rotational part assembled by overmolding showed in testing that it was significantly weaker than the all-metal current production part. In other verification testing, for significantly different rotational components made with thermoset adhesive to bond the composite to the textured metal, all of the components survived the entire duty cycle for that component, as did the current all-steel part. This thermoset adhesive method of assembly was fully successful, and indicates a significant method for successful joining of metal and composite. A dynamometer test cell for rotational eqipment is shown in Fig. 12.8, with the dissimilar material component inside the blue housing. 12.5.3 Full Prototype Dynamometer Duty Cycles For full-scale testing, on various drivetrain components, the material choice, processing, surface preparation, and component loading for the duty cycle, influence the outcome of the verification testing. Although there were mixed reports in the described results, the outcome is dependent on multiple inputs, making broad conclusions difficult. But it is clear that certain designs and materials in drivetrains, with cylindrical geometries, can be made successfully, by use of large interface-areas with mechanical-interlocks, with the appropriate choices of materials, process, and interface bonding method. Fig. 12.8 Metal-andcomposite components are prototyped full-scale and tested inside existing subassemblies as shown in the dynamometer test cell here 12 Metal-to-Composite Structural Joining for Drivetrain Applications
RkJQdWJsaXNoZXIy MTMzNzEzMQ==