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Written by: Stuart Sampson, vice president, HyperWorks Enterprise Implementations at Altair Engineering, Inc.; Dr. Lars Fredriksson, vice president, Global Automotive Business, Altair; and Dipl.-Wirt. Ing. Mirko Bromberger, director of Marketing Strategy, Altair 

Design with Engineering Plastics – Reduce is Better than Recycle

One of the main benefits of engineering plastics is their ability to offer material properties enabling high performance at low weight. As such, they are ideal for meeting the requirements of a complex lightweight part. However, the design of such parts is complex, as not only the specific material properties but also manufacturing requirements must be considered. In addition, automotive electrification brings changing interior acoustics and new packaging requirements for electric vehicles. A new design approach is needed to achieve a balance between structural and acoustic performance requirements while meeting weight and cost targets.

This is where the holistic simulation of engineering plastics comes in. Focusing on the prediction of noise, vibration and harshness (NVH) behavior of the components, this method should form the basis for material and design decisions in the early concept phase.

Design Example: Developing Optimized Structural Reinforcements

L&L Products, Inc., based in Altorf, France, creates solutions for applications requiring static sealing, better acoustics, reduced vibration, structural reinforcement and thermal management, while improving manufacturing process optimization. The company’s Composite Body Solutions (CBS) help reduce structural weight and noise while improving the overall stiffness and crash performance of the body-in-white. Specifically, the products are applied in lightweight structural applications such as those required by battery protection for electric vehicles (EVs).

L&L Products' three-step CBS development process traditionally included CAE model extraction, build space creation with CAD and topology optimization, which needed both CAE and CAD resources. L&L Products turned to Altair to optimize the resource-intensive workflow. The goal was to streamline the development process by enabling computational engineers to create the necessary design space models themselves using appropriate CAE tools. This is made possible by Altair's new design space approach within the Altair HyperWorks environment.

The "Local Design Space" feature provides the ability to automatically create design space models by filling existing cavities with voxel elements and then connecting them to adjacent structural components. The fast and flexible definition of design spaces by reusing pre-selected boundary conditions allows users to analyze different variants in seconds.

In contrast to the previous three-step method, which took about an hour per area, the new workflow requires only a couple of minutes.  By creating a local voxel mesh, the new workflow does not require in-depth CAD expertise. The new Altair approach not only reduces modeling time significantly, but also fits seamlessly into L&L Products' existing product development process and ensures comparable accuracy of simulation results.

Is Topology Optimization Strategically Applied?

Topology optimization has been used and applied for decades, and in an increasing number of applications has proven helpful to reach an optimal and balanced design that considers weight, cost and performance. Especially when established designs need to be rethought to allow, for example, a material substitution or to consider different manufacturing methods, topology optimization becomes the foundation of sustainable design concepts. However, it often requires organizational changes to development processes in order to strategically leverage the benefit. In particular, the definition of the available package space has been an obstacle in the past.

Based on the findings of previous projects that streamlined the processes around topology optimization, companies are developing new processes for building engineering workflows. These accelerate and ease the application of topology optimization as a strategic enabler for mass reduction and facilitates sustainable design for parts and sub-systems.

Here we discuss three application areas where new CAE Workflows enable Design for Sustainability in i) global vehicle architecture, ii) local structural body reinforcements and iii) the optimal distribution of structural adhesives. Based on recent use cases, the performance, time-savings and business impact will be described.

A Holistic Approach

When designing load bearing plastic inserts to improve the NVH performance of a vehicle body, sensitivity analyses come first in order to determine the parameters which significantly influence the component properties. The resulting parameters are then optimized to find the best concept by finding a balance between maximum performance at lowest weight. Topology optimization is an important design tool that is most effective when used as early as possible in the development phase. The topology of a component ensures design concepts are feasible regarding loading and manufacturability right from the start.

Organizational Roadblocks and Transformation

For several years, Altair has been developing and promoting their C123 body and architecture concept development process. The C123 approach is a development strategy supporting body, platform and architecture development from the feasibility stage until handover to mainstream development. It focuses on actively supporting development decision-making and the maturing process by systematic deployment of simulation and optimization. A massive amount of trade-off and design exploration information is generated to support the uncertain nature of early development in a timely manner. The fidelity of models is adopted during the process to provide the best compromise between fast decision making and accurate results during all stages of the process.

Considering an OEM process program timeline, the different logical phases can be explained as follows:

C1 - Load Path Development

Lots of freedom for changes, cost of change, design ideas and feasibility studies to understand modular design, carry-over content and general design balance limits.

C2 - Mature Sections and Joints

Efficient design exploration using right-fidelity models, what-if studies to help choose and dimension cross sections and structural joints.

C3 - Verify and Prepare Hand-Over to Mainstream Development

Start to get into details with full-scale multi-disciplinary optimization and move into the product development phase.

Who Has the Responsibility for the Design Space Creation?

The development and application of the C123 methodology has led to a variety of process and software innovations to accelerate and democratize the concept development process. Provision and update of accurate design space information are key factors for the successful application of topology optimization or generative design. Thus, both from an organizational and a methodology point of view, it is important that the creation and updating of design space is well integrated into the methodology.

While styling provides the outer envelope for design, many different functional attributes are fighting for available space, leading to a need to efficiently manage how the total design space is used.

Overcome Obstacles

The basis for a strategic application of topology optimization is an efficient design space generation. However, this is not an easy task for several reasons. For one, there is often a lack of suitable tools. Secondly, the involvement of several departments leads to considerable time delays. To fully exploit the potential of topology optimization and enable faster and better decisions, the required input variables must be available as early as possible. To achieve this, the barriers between the CAD design and CAE departments must be removed.

Altair has developed a set of new process building blocks which help simplify the use of topology optimization as a strategic key to lightweight design and the development of sustainable components and systems. Significant time savings can be achieved in model generation, which leaves more time for evaluating variants and improving the design.

Experience Altair HyperWorks - Design Space Management for Topology Optimization. (Video courtesy of Altair.)

Unlocking the Potential

If put side-by-side with the traditional approach, the new processes reduce manual effort, unify disparate tasks from different departments into a single workflow, and significantly shorten modeling time This saves development time, allowing engineering teams to focus on more creative engineering work.

In fact, the time saving potential for the whole development project is even greater. The example below shows the time savings for only a single structure node. However, such structural nodes are required at several points in a vehicle body. So this time saving of 80% in model development can be multiplied by the number of components developed. 

Applying topology optimization increases design confidence and leads to cost savings as well as significant material savings. In particular, when established designs need to be redesigned because of material substitution or changed load or boundary conditions, the Altair approach of strategic use of topology optimization at various levels of vehicle development results in a sustainable use of plastic materials.  Following the motto "material that was not used in the first place does not have to be recycled," this methodology is a milestone for the development of sustainable plastics solutions.

To learn more, visit Altair.

About the Authors

Stuart Sampson is vice president, HyperWorks Enterprise Implementations at Altair Engineering, Inc.

Dr. Lars Fredriksson is vice president, Global Automotive Business Altair.

Dipl.-Wirt. Ing. Mirko Bromberger is director marketing strategy Altair.