Car Crash Simulation

What actually happens during a car crash? How does each part of the car react? What are the specific effects on passengers? To design safer cars you need to fully understand accidents. Software simulations help uncover the deadliest dangers—and test solutions.

More than 30,000 people die every year on American roads. Too many—but far fewer than a generation ago, thanks largely to seat belts and knowledge gained from simulations.

Software can simulate the real world. But it can’t replace the real world. So car design engineers combine information from virtual crashes and from actual crashes.

Simulations let engineers explore varied options early in the design process. But final, definitive tests, the basis for safety ratings, require smashing real cars.

Creating an actual car crash is easy (unfortunately). But how do you create a simulation?

Once designers have outlined a car’s basic form, they use the finite element method (FEM) to model its shape by plotting many interconnected points on the car’s surface.

Software then calculates how the forces in a crash would affect each of those points to determine the overall result of the impact.

Appearance. Performance. Efficiency. Safety. Cost. Computer-aided design (CAD) lets car designers balance all these factors, simulating the performance and tweaking the look of each new model before building actual prototypes.

Auto manufacturers adopted many CAD techniques from aeronautical engineers, who pioneered the use of powerful computers to model the performance of aircraft designs.

Software simulations play a part beyond crash tests. They touch every step, from design and engineering through production.

For example, fluid dynamics computations analyze aerodynamics to improve fuel efficiency. Performance tests provide feedback as the design evolves. And simulating the manufacturing process identifies ways to increase efficiency or reduce waste.

There are many steps in designing, testing, and building a safe, stylish car. Software plays a central role in each.

Design

Computer-aided Design (CAD) software transforms ideas into images, showing how the car will look, and creating a data set representing the car.

“Mesh” Engineering

Using the CAD data, a finite element method (FEM) engineer creates a graphical “mesh,” plotting each car part as a mosaic of small polygons called “elements.” Software assembles each individual element into a complete and structurally accurate mesh model of the car.

Simulated Crash

Finally, engineers crash the car into a barrier—virtually—using powerful software to simulate the effect on each element. The system displays the results as a moving image, which engineers use as a guide to fine-tune the design.

Software that makes cars safer was originally developed to help blow things up.

In 1976, John Hallquist at Lawrence Livermore National Laboratory (LLNL) created DYNA3D, which used the finite element method to measure the impact of nuclear bombs dropped at low altitudes. Its unique 3-D capabilities became the foundation for commercial software that simulated car crashes.

The earliest simulations produced pages of numerical data, which engineers had to interpret. Today, powerful computers turn this data into graphics, letting engineers watch moving images of car crashes, greatly simplifying their analysis of the results.

The more powerful the computer, the more complex, accurate, and easily interpreted the simulation.

Engineers want to know what happens to cars during crashes. Even more, they need to know what happens to passengers.

Before computer simulations, crash tests used animals, cadavers…and volunteers. But there’s only so much you can learn from a cadaver. And only so much you can do to a volunteer.