Simulation software: from parts to manufacturing

Features - Software

Design simulation tools allow automakers to test parts, not only for shape and structural integrity, but to see how well they fit into modern plant assembly operations and real-world driving conditions.

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The seating engineers at BMW knew the new rear seat designs for the 3-Series car line would fit into the space allotted, but that wasn’t the question.

Could a plastic, injection-molded support offer as much passenger protection as the steel assemblies it would replace? Could employees install the single piece in a space designed for a multi-part assembly? Would the bending and twisting of the part in the assembly process hurt structural integrity?

With those and other questions unanswered, building molds and creating test parts sounded like an expensive, time-consuming risk. So BMW’s designers turned to Autodesk’s simulation software. Creating CAD files of parts and vehicle designs is a standard process in most manufacturing operations. Running those digital files through simulations of the part-creating process, vehicle assembly operations, and crash-test conditions was new for the automaker.

“The trend we see is OEMs are not interested in simulating a single part. They want to see how the part interacts within the system,” explains Derrek Cooper, Autodesk’s director of product management for digital simulation. “People are going beyond the discrete part and seeing simulation of the manufacturing and mounting of the different pieces and the installation on the final vehicle.”

Cutting weight would be useless if it risked the company’s reputation for safe cars. So BMW used the simulation to test the quality of the seating supports.

Using Autodesk’s Moldflow software, the automaker was able to design the seating supports and optimize its shape and material properties. The software analyzed the efficiency of the part in terms of what molds would be needed for manufacturing it, how assemblers would fit into the car, and its durability.

“After the optimization software tests, they built a first mold and found that part worked perfectly and quickly moved into production,” Cooper says.
 

Variety speeds the design process

Such simulation projects are becoming more common as automakers accelerate their design processes. The days of keeping a vehicle platform basically the same for eight or nine years are over. Car companies are now redesigning vehicles every three to five years, and mid-cycle upgrades are more radical – often involving new engine options, completely different instrument panels, and coupe or hatchback options.

Stephen Hooper, Autodesk’s director of automotive products, says the amount of design work in the auto industry has increased dramatically. To cut development times and costs, OEMs are sharing engines, transmissions, suspensions, and other mechanical components across multiple vehicles. Designers need to individually style multiple vehicles based on those shared architectures.

“The variety of vehicles is increasing,” Hooper says. Designers “have to create more concepts in the same amount of time. They have to differentiate the variety of vehicles based on similar platforms in terms of styling and performance.”

Multiple new designs mean multiple unique parts for each vehicle, and those parts must be cleared as manufacturable, safe, and cost effective. Physically manufacturing a test part for each unique piece is expensive and time consuming, and Hooper says many OEMs are turining to digital tools to verify specifications instead.

Next generation design Software

As choices increase for automakers, designers want to test parts in as many materials as possible.

Cloud-based software helps Autodesk better handle such requests. While current software runs each possible material choice in order, identifying strengths and weaknesses, cloud-computer clusters can have dozens of computers run a single simulation. Simultaneous simulations reduce the time needed to analyze choices.

“Sometimes, I want to try 10 simulation models of a part in different materials and processes. Sometimes I want to try 100 models. Each model requires time and processing power. Those are the limits right now, but that’s going to be changing,” says Derrek Cooper, director of product management for digital simulation at Autodesk.

Advanced algorithms can analyze the results of modeling runs, pointing designers to the best materials choices.

Those capabilities should also help car companies further differentiate mechanically similar vehicles – choosing plastic parts for one model, carbon fiber for another, and steel for a third will give each model unique characteristics.

“There can be thousands of correct results for materials and processes. Manufacturers have a lot of choices that will all work well,” Cooper states. “The best fit is going to be different for every vehicle, so we’re going to have to show lots of different options.”

Cooper says simulation tools are among Autodesk’s fastest-growing products. “The number of parts you have to customize on each vehicle goes up every year. Each fabric choice must be designed and verified: every trim piece, every bit of chrome. To physically manufacture those – to build the mold and make the piece in the proper material, just to validate the part – wouldn’t be economically viable.”

Often, simulations reveal problems in how parts will be installed. With a car bumper, for example, designers can simulate the plastic injection molding process, then run the simulated part through a virtual mounting assembly process.

After simulation, engineers and designers can use software again to test the new part’s projected performance under harsh conditions. With mounting brackets in the engine compartment, for example, engineers can predict how parts will react on a bitterly cold day, starting at -20°F then quickly surviving high temperatures as the engine warms.

“There really are no discrete parts on a car. Everything fits together, so the more you know about when and where each part fits into that puzzle, the better off the process is going to be,” Cooper explains.
 

Lightweight design

Simulation becomes more critical when cutting vehicle weight. Automakers constantly test new materials to shave every ounce possible from designs. Every 100 lb of vehicle weight saved roughly equals 1mpg, so every steel part replaced with aluminum, plastic, carbon fiber, or magnesium helps companies get one step closer to stringent 2025 fuel economy regulations.

Design software can analyze the impact of running different parts in various materials – assessing whether or not a lighter-weight version is as crash worthy or cost effective as the steel equivalent. Simulating the expected performances with advanced software tools helps companies determine the best option for each component.

While faster than building test parts, simulating parts in dozens of materials takes times and requires a lot of computing power. Some software companies, including Autodesk, offer cloud-based versions of their software so users don’t have to worry about the amount of computing power needed to run so many simulations.

Hooper says these software upgrades are necessary to keep up with the breakneck design pace automakers have set. Designers need to produce more options in less time and less manpower. Suppliers that can improve that process stand to gain.

“There are some radical changes going on in the design and manufacturing of cars, so we have to be just as radical in the tools we’re offering,” Hooper states.


Autodesk Inc.
www.autodesk.com

 

About the author: Robert Schoenberger is the editor of TMV and can be reached at 330.523.5381 or rschoenberger@gie.net.