Car Crash Simulation

Simulating Safety

Would you volunteer to drive into a brick wall? Probably not. Which is why computer simulations are crucial to auto safety.

Software lets engineers run crash tests inside computers rather than on roads. It also allows them to compare the performance of different designs early in the process while cars are still on the drawing board, saving money and injuries.

Impact

When Software Saves Lives

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.

Credit: Cray Research Inc.

Real and simulated crash test. Simulation performed on Cray supercomputer

Simulated crashes help engineers design safer cars. Note how the front of the car crumples and absorbs most of the impact, protecting the passenger compartment.

Computers vs. Crashes

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.

Deaths per billion miles traveled, 2014

Credit: Derived from the Insurance Institute for Highway Safety

Deaths per billion miles traveled, 2014

Cars have become much safer over the years. From 1950 to 2014, the US population increased by over 150 million yet the rate of car crash deaths declined by more than half.

Engineers instrumenting prototype for crash test

GAUTIER Stephane/Alamy Stock Photo

Engineers instrumenting prototype for crash test

A lot happens during a real crash test and it happens fast. To capture crash data, engineers place sensors throughout the test car.

Test engineer monitoring car crash on computer

Agencja Fotograficzna Caro/Alamy Stock Photo

Test engineer monitoring car crash on computer

Crash tests take place in “crash halls.” While engineers oversee tests on computer screens, the actual crash data is stored in digital recorders in the car.

Real and simulated car crash, May 2014

Credit: Honda R&D Americas Inc.

Real and simulated car crash, May 2014

Comparing results from crash simulations with real crash tests improves the accuracy of both. Software engineers fine-tune their models based on real-world results.

Stutz ad, 1925

Stutz ad, 1925

Pontiac Bonneville Super Chief and Star Chief advertisement, 1958

Pontiac Bonneville Super Chief and Star Chief advertisement, 1958

”Auto Issue,” <em>Consumer Reports</em>, April 2016

”Auto Issue,” Consumer Reports, April 2016

Car Crash Simulation Poster

Car Crash Simulation Software Makers and Users

Crashed Ford Taurus, 2008

Crashed Ford Taurus, 2008

Technology

Creating a Virtual Crash

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.

Car model by George Washington University, 2012. Image courtesy of Livermore Software Technology Corporation.

Car crash simulation using LS-DYNA software, 2016

This virtual car simulation, shown in the program LS-DYNA, shows the FEM “mesh” covering the car. Each point in the mesh represents a series of calculations.

CAD in Auto Design

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.

Engineer using DAC-1 at GM Research Laboratories, 1966

Courtesy of General Motors

Engineer using DAC-1 at GM Research Laboratories, 1966

In 1964 General Motors and IBM announced the DAC-1 computer-aided design system for cars. The system acted as an electronic sketchpad and controlled a milling machine to produce a physical model.

Aircraft wing FEM, 2015

Aircraft wing FEM, 2015

1/5th-scale 2020 Buick Skylark concept model, 2014

1/5th-scale 2020 Buick Skylark concept model, 2014

From Concept to Construction

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.

Minivan CFD simulation, 2008

Courtesy of Murtazo Nazarov, Uppsala University (geometry courtesy of Volvo Car Corporation)

Minivan CFD simulation, 2008

To improve fuel economy, car manufacturers try to reduce wind resistance. Computational fluid dynamics (CFD) simulations show how air moves around a moving object, like this minivan, allowing designers to adjust its shape.

Disassembled Saturn S Series, 2000

Disassembled Saturn S Series, 2000

<strong>Top</strong>-1984 Camaro lift window outer panel (outlined) <strong>Middle</strong>-Stamped sheet metal. Lift window outer panel <strong>Bottom</strong>-CAD screenshot

Top-1984 Camaro lift window outer panel (outlined) Middle-Stamped sheet metal. Lift window outer panel Bottom-CAD screenshot

Simulation Software

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.

CAD model of car using 3DCS analysis software, 2012

Courtesy of 3DCS

CAD model of car using 3DCS analysis software, 2012

FEM mesh in CAD

FEM mesh in CAD

DYNA3D simulated car crash (detail), 2016

DYNA3D simulated car crash (detail), 2016

History

The Origins of Crash Test Software

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.

ABLE bomb test, part of Operation Crossroads, 1946

Credit: US Department of Defense (public domain)

ABLE bomb test, part of Operation Crossroads, 1946

LS-DYNA, the earliest crash test software, grew out of nuclear weapons research at LLNL in the mid-1970s.

LLNL aerial view, ca. 1997

Credit: National Ignition Facility, Lawrence Livermore National Laboratory (public domain).

LLNL aerial view, ca. 1997

Nearly 6,000 people work within LLNL’s one-square-mile area. Since the 1950s, most US nuclear weapons have been designed there and at Los Alamos National Laboratory in New Mexico.

John Hallquist, 2014

John Hallquist, 2014

John Hallquist creator of the earliest crash test software Poster

John Hallquist creator of the earliest crash test software, LS-DYNA (originally called DYNA3D)

DYNA3D user’s manual, ca. 1976

DYNA3D user’s manual, ca. 1976

Graphics Help the Engineer

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 with numerical printout, October 12, 1981

Credit: © ITAR-TASS Photo Agency/Alamy Stock Photo

Engineers with numerical printout, October 12, 1981

Before graphical workstations, car designers and engineers had to interpret simulation results in tables of numbers, like the one seen here.

Comparison of simulated and physical crash test results of VW Polo simulation, 1986

Comparison of simulated and physical crash test results of VW Polo simulation, 1986

Cray T90 supercomputer system, February 1995

Cray T90 supercomputer system, February 1995

Crash Test Stands-Ins

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.

Crash test dummies go to class

Credit: RGB Ventures/SuperStock/Alamy Stock Photo.

Crash test dummies go to class

Crash test dummies are used to study the effects of crashes on humans. Modern dummies contain over 200 data sensors used by engineers to anaylze a crash’s impact on individual body parts.

Audi crash test dummy family

Credit: Jon Riley/Getty Images

Audi crash test dummy family

Since the 1950s, crash test dummies have evolved from a single dummy to entire families. Today, dummies represent different sizes, weights, and heights, providing engineers with more accurate results during crash tests.

Rusty Haight, ARC-CSI Crash Conference, Las Vegas, Nevada, June 4, 2012

Rusty Haight, ARC-CSI Crash Conference, Las Vegas, Nevada, June 4, 2012

Priya Prasad, Technical Fellow (retired) at Ford Motor CompanyPoster

Priya Prasad, Technical Fellow (retired) at Ford Motor Company