CALM Report: Mixed-Materials Approach Yields Up to 65% Weight Savings

By on April 21, 2017 in MATERIAL MATTERS

The Coalition for Automotive Lightweighting Materials (CALM) has completed phase one of a collaborative project that seeks to lower the weight of a known vehicle door assembly by examining advanced mixed-material and process solutions.

By the Center for Automotive Research

Automakers are making significant strides through ongoing efforts to remove additional weight from next-generation vehicle models. In response to ever-more challenging fuel-economy and greenhouse-gas regulations, these automakers continue to rely on lightweighting as a key means to meeting established goals.

The Coalition for Automotive Lightweighting Materials (CALM) has completed phase one of a collaborative project that seeks to lower the weight of an existing vehicle door assembly by examining advanced mixed-material and process solutions. By fostering pre-competitive communication and collaboration between and among competing suppliers, the project helps demonstrate and accelerate the introduction of lightweighting technologies. Through this process, the co-development team offers a dozen integrated solutions deploying a mix of materials and technologies. Weight reduction for a baseline door assembly used in the project reached up to 65 percent weight savings compared to the initial, mild steel-based design. Every technology and process included in the project is available and ready for deployment in the design of new vehicles.

The report, “Mixed Materials Solutions: Alternative Materials for Door Assemblies,” was published by the Center for Automotive Research (CAR) and reveals the collaborative contributions of more than 20 supplier companies and two trade associations. There are a dozen integrated solutions in the report, deploying a mix of materials and technologies allowing weight reduction up to 65 percent weight savings compared to a baseline design.

The CAR report aims to identify mixed-material solutions that reduce weight in vehicle assemblies by providing technical solutions with results exceeding an established baseline and by linking process technologies with multi-material solutions.

Collaborative Approach & Method

A yearlong pre-competitive endeavor by a cross-functional team of partners and competitors joined to develop industry leading-edge technologies. It is a unique effort for providing automotive manufacturers with innovative mixed-material solutions. While companies want maximize the material and/or process they market, each recognizes the need to optimize the cost and performance of any solution. Having fierce rivals working together to come up with alternative solutions may be an industry first.

Establishing the Baseline

The CALM coalition chose the EPA’s study of the 2011 Chevrolet Silverado as the project’s baseline. The study conducted by FEV analyzed the ability to decrease the Silverado’s weight using known materials and processes. This extensive report preserved the product design while altering material technologies to make the vehicle lighter. The CALM team chose the Silverado door system and data from this report because it included detailed information on the closures, enough so that the team could complete the phase-one work. Using what was available in a public forum meant the group was not bound by the proprietary data of a single automaker.

The 2011 Silverado door was fundamentally a mild steel design, with a high-strength steel crash bar and inner reinforcements. The CALM team focused on five major components of the door—the outer and inner panel, crash bar, reinforcement and hinges. These five represent 80 percent (29 kg) of the total door weight. The removed door pads, switches, motors and glass represent further opportunities to reduce weight, but were considered out of scope of the team’s phase-one efforts.

Method

The CALM team met regularly with member company representatives, who participated in brainstorming ideas, calculations and debate of merit, and the preparation and editing of presentation materials for OEMs, demonstrating the potential weight savings available with mixed-material solutions. The role of the participating companies went beyond submitting ideas. The team collectively reviewed more than 50 potential enabling technologies and worked together to evaluate the merits of each idea, along with the associated processes required for potential application. As a result of this rigorous process, the list of ideas was reduced to a dozen key combinations for the current term, all of which are production ready to the industry today (2015). Each scenario represents multiple concepts capable of being implemented now without need for extensive additional research and development. Examples of technology in other automotive components are used to demonstrate its feasibility and readiness. Finally, the team considered a number of future concepts, requiring direct work with an OEM for further development.

Quick Assessment Tool

The group developed a quick assessment model for “what if . . .” scenarios to analyze the weight reductions possible when base material, material grade or thickness are changed. Although only a first step, it provides a rough test to quickly determine whether particular solutions showed merit, while identifying others that would be fruitless to pursue.

While a full design execution project would require significant engineering modeling and finite element analysis (FEA) to prove actual results, the coalition leveraged this assessment tool to look at promising opportunities. As the coalition intended from the outset to review these opportunities with OEMs, a first-phase initiative needed results that would carry forward into a second-phase project and apply to a new design with complete modeling and analysis.

A fundamental discovery along the way was the lack of any single best or worst case design. There was no clear winner or loser among the mix of materials. Each design solution has an optimal volume niche, production rate, cost and performance capability. Not all vehicles require the same solution, so the study resulted in a suite of solutions with each mix of materials best suited to a particular application.

Read the rest of this feature article in the current issue of Lightweighting World.
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