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SEP 2018

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NEWS CompositesWorld.com 35 Hollow-profile Hybrids count and production steps not only reduces cost and the manu- facturing footprint, but it also reduces inventory and warranty costs. And because its matrix is a thermoplastic, the hybrid struc- ture can be separated and recycled at end of vehicle life. Because of its recyclability and performance benefits, PMH technology has been used for many years to produce a variety of automotive components, from large assemblies like front-end modules and bumper beams to underhood components. It also has been used in nonautomotive applications, such as roller- blades, and components on scooters and small, off-road cars. Tubular structures As is true of any technology, PMH has a few disadvantages. First, amortization of metal and plastic tooling costs (both types are needed with this technique) is likely to necessitate application to medium- to high-volume vehicle programs. It's too costly for niche production unless tooling costs can be shared with similar models on the same platform. Second, as conven- tionally applied, PMH technology is best used with simple 2D or 2.5D sheet-metal substructures, e.g., L-, C-shaped or flatter sections. However, those structures often lack sufficient torsional strength to meet certain high-performance require- ments. Also, it's not possible to make closed-form/tubular structures (think O-section and other tubular or square cross sections) via PMH because a closed profile would collapse under the high pressures of injection molding. "e idea for hollow-profile hybrid structures evolved from a list of high-load structural automotive applications, where it was highly desirable to reduce mass and add functional integration, but where current PMH technology wasn't strong enough to meet performance require- ments," explains Joseph Aiello, LANXESS structural application development engineer. He cites the cross-car beam as a theoretically ideal HPH component, since it's heavy and contains a multitude of brackets and other attachments in metal. Cross-car beams are used on every passenger vehicle to provide torsional rigidity to the chassis. ey also provide attachment points for components that penetrate from the engine compartment into the vehicle interior (e.g., steering wheels) and for components that attach from points in front of the firewall and project into the passenger cabin (e.g., instrument panels and center consoles). Prior work applying PMH tech- nology to a cross-car beam lacked sufficient mechanical perfor- mance because the effort centered around an attempt to create the tubular (closed-form) metallic substructures for the beam by welding two open, L-shaped PMH structures together after they were overmolded. "Since a closed-form structure is well known in engineering to be stronger than an open structure, a logical place

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