Multi-Material Lightweighting with Optimization-LED Design

Introducing a performance-driven, holistic product-development method

Lightweighting is a major focus in product design and development for ground transportation vehicles (passenger cars, trucks, buses) and many other consumer items. It is a multipurpose, economical solution for many industries, including environmental, construction and transportation.Product cost, CO2 emissions (increasing 34.1 mpg 2016 to 54.5 mpg by the 2025), shipping and transportation costs reductions are just a few things that are impacted by lightweighting in product development.

For OEMs and suppliers, lightweighting is an uphill battle in which they must design and develop products that require a balance between a variety of competing factors. The factors include cost, mass, multidisciplinary performance, multi-material function, joining and manufacturability. Furthermore, they must achieve this balance while meeting high government and consumer standards.

The key to lightweighting lies in using multi-material products. The future of product design and development for electric vehicles (EV) and battery electric vehicles (BEV) relies on these types of materials. One of the most difficult tasks for manufacturers is the proper use of materials, the choice of advanced materials (advanced high-strength steel, aluminum and carbon fiber plastic), placed in the proper location with the optimal geometry, grades and gauges.

To assist in the product design and development process, companies facing these challenges use a systematic optimization-led process, software and multi-materials to create products that are lightweight, cost efficient and which meet all the performance requirements.


Technology Begins Driving Innovation

As Steve Jobs once said, “Innovation distinguishes between a leader and a follower.” Very true in this ever-changing world, and yet, technology continues to be the driver behind that innovation.

This is certainly accurate in describing the product design and development space today. With high-performance cluster computers (having increasing speed and memory), CAD model parameterization and multi-disciplinary optimization tools, as well as new analysis software tools, new methods of product development are now being utilized. This is because the design of complex structures is driven by many competing criteria, such as cost and weight reduction, contrasted by enhanced multi-disciplinary performance and manufacturability constraints. New technology is required to solve these challenges head on.

Furthermore, the introduction of new manufacturing processes and advanced materials, such as carbon fiber, advanced high-strength steel (AHSS), aluminum and magnesium, significantly increase the available design space. A broader design space expands the set of all possible options for mechanical systems, putting the optimal design within reach.

To explore the entire design space more effectively, while trying to reduce design-cycle times, engineers at Engineering Technology Associates, Inc. (ETA) developed an automated way of using optimization to drive the design process. They made design optimization a virtual search engine resulting in hundreds of concept possibilities that meet design criteria and constraints at varying degrees. Like plots on a diagram, the optimal design concept can be found when the most ideal balance is met.

Steve Jobs said, ”Innovation distinguishes between a leader and a follower.” True, yet, technology continues to be the driver behind that innovation.

Fig. 1 – Benefits of the ACP Process

Evolving over the last decade, the methodology used is the Accelerated Concept to Product (ACP) Process®, a performance-driven, holistic product-development method based on design optimization. The methodology combines design, material and manufacturing expertise with CAD, CAE and CAO tools. As a result, product development time, resources, cost and product mass is reduced, while overall product performance and time to market is improved. (See Figure 1.)

Using the ACP Process, the engineer can easily find the optimal balance of structure and strength, and greatly decrease the time required to identify a set of feasible, or even optimal, designs prior to building and testing the first prototype. The methodology has proved that it could also compensate for the limitations of human intuition and provide design engineers with the freedom and power to seek creative solutions that are not obvious to even the most experienced design engineer.

In 2015, ETA joined forces with BETA CAE Systems, an innovation leader in engineering software specializing in state-of-the-art CAE pre/post-processing software systems, to form a unique collaboration. The partnership combined ETA’s ACP Process with BETA CAE System’s powerful software platform, ANSA, into a new product called ACP OpDesign. Currently undergoing benchmark testing at a major auto manufacturer, the tool will be released to the public in the fourth quarter of 2018.

ACP OpDesign provides two major functions for product design and development. First, it acts as an optimization suite, which allows the engineer to perform any type of design optimization. It offers an easy and effective gateway to commercial optimization and solvers. Second, led by design optimization, it provides tools to design structural products from concept to production.

Using ACP OpDesign, various shape (geometry), gauge and material-grade design variables are set up using ANSA’s morphing and optimization setup functionality. This is also known as 3G Optimization. Post-processing is done through automated META sessions, which track and report responses for all runs. Optimization tools provide easy-to-use and simple-to-understand optimization results. CAE, design and manufacturing are all synchronized to find the optimal design solution using multiple CAE tools, application-specific tools, solver technologies and optimization solutions.

The process is arranged in three phases. Concept, Low Fidelity 3G and Decoupling & High Fidelity 3G. The user can either apply the process starting from the Concept phase or separately using legacy designs to optimize. (See Figure 2.)


Concept Phase

Starting from Concept, the available design space is defined and set up for topology optimization under multidisciplinary loads, both static and dynamic. The shell geometry from the results is generated by allocating material where it is needed to withstand the loads. There are sub-tasks that are completed in this phase, including design definition and creation, load case setup, topology optimization and 3-D shell geometry. The final step is the load path mapping.

 

Fig. 2 – The Phases of the ACP Process

 

Fig. 3 – Rear of the FutureSteelVehicle design after applying the process


Low Fidelity 3G (LF3G)

Continuing from a Concept design or starting from an existing design, LF3G focuses on the optimization of the geometry, grades and gauges. This step optimizes the position of important parts, the width and height of the cross sections, the types of material and the material grades. The sub-tasks include positioning and cross-section parameterization, thickness and material parametrization and finally parametric optimization.


Decoupling and High Fidelity

Based on alternative manufacturing design solutions, important load-carrying sub-systems are “decoupled” for a detailed design in this phase. These sub-systems are further improved under multiple load cases. Further, the system is fully reintegrated, and gauges are optimized, if required. Again, various sub-tasks are needed. First, full system’s load cases are defined. The sub-system is then decoupled, and boundary conditions and load conditions are applied (sub-structuring). Finally, manufacturing processes are chosen, and the sub-system is recoupled. (See Figure 3.)

All required tasks and modeling processes can be either completed within the software or by calling the required tool from within the interface.


ACP OpDesign Architecture

ACP OpDesign is client developed to band with the advanced management software SPDRM and ANSA/EPILYSIS/META suite, all products of BETA CAE Systems. Mapping ETA’s ACP Process, it cooperates with all mainstream optimizers and solvers to complete even the most-demanding optimization task. The architecture makes this process possible.

With an intuitive user interface, ACP OpDesign helps the user move forward in the optimization processes with a clear image of the required tasks to be performed in each phase.

The management capabilities incorporated within the product allow the user to work with data effortlessly. All required tasks and modeling processes can be either completed within the software or by calling the required tool from within the interface. The user can connect directly in a process orientated, easily understood manner. For example, using the Data tab, the user can save and retrieve data from the system’s database. Also, the Process Progress and Task tabs are arranged according to the three phases of the ACP Process.


Dedicated Tools

In addition to the industry-proven, pre-existing tools that realize the ACP process, ACP OpDesign features a list of tools designed and developed in the context of actual optimization projects. Such tools include the Load Case Manager, Skinning, Simulation Manager, Sub-structure and Manufacturability.

The Load Case Manager lets the user create static (NASTRAN, LS-DYNA Implicit) or crash load cases (LS-DYNA Explicit), which will be used during the process. Loads, BCs, barriers, velocities can be defined within the tool with the aid of ANSA.

With Skinning, the user easily creates the geometry of the final skeleton from topology optimization results during the Concept phase. It offers an easy and fast way to not only create the geometry based on the selected cross section, but also to automatically treat the connected geometries.

The Simulation manager lets the user monitor the job’s status. With this tool, the user can modify significant solution parameters, such as memory, CPU number and which machine to use. It has a tool with all actions related to simulation. The simulation jobs that have to be submitted during the process are prepared in the Load Case Manager and are fed automatically to the Simulation Manager.

With the aid of dedicated tools in Substructuring and Manufacturability, the user can “decouple” important load-carrying sub-systems easily to further enhance their design. Taking into consideration the manufacturing alternatives, the best solution is then “recoupled” into the original system.


In Summary

ACP OpDesign can be applied to a wide range of structural products in a variety of industries, including automotive, aerospace, heavy truck, packaging, appliance and many others. ACP OpDesign is a gateway to a wide variety of tools and promises to revolutionize the product design and development process, making a wide array of structural products lighter, cheaper, stronger and more efficient.

 

By Dr. Akbar Farahani

Dr. Akbar Farahani,
Vice President and Director of Global Engineering and Software, ETA Inc. Dr. Akbar Farahani has more than 30 years of experience in CAE and product design development and consulting for automotive OEMs and suppliers, including GM, Ford, Chrysler, Nissan, Toyota, Honda, Kia and Hyundai. His areas of expertise include method development for product design and development using CAE, such as the Virtual Proving Ground (VPG) software and optimization technology (topology and parametric).

In the past 15 years, Dr. Farahani focused on lightweighting technologies and design solutions, investigating material options and manufacturing processes for full vehicle system and chassis/suspension. He led the development of ETA’s Patented Technology “ACP Process” (Accelerated Concept to Product Process) and ACP OpDesign (optimization led design software).

Dr. Farahani received his bachelor’s degree in civil engineering from the University of Nevada and a master’s from the University of California, Irvine in structural dynamics. He received his Ph.D. in civil engineering/structural mechanics from BYU.

Top