Design Analysis

Exponent provides design analysis services to meet a wide range of client objectives. One client may be faced with a potential regulatory issue and wish to have an independent assessment of product safety. Another client may be interested in buying a product to incorporate into a system they are developing. A manufacturer may be looking for new ideas to help them bring a design to production. All of these clients can benefit from coming to Exponent. Whether it's a new way of analyzing the design, or a unique test methodology that ultimately helps them over their design obstacle, we have expertise they can rely on.

Because conventional test methods don't always provide answers to our clients' questions, Exponent frequently develops new test methodologies and systems. Exponent conducts not only full system tests but also tests focused on specific components or subsystems. Frequently, the client does not know what kinds of tests should be run in order to answer their questions. This is where our experience in testing hundreds of products becomes invaluable.

Not only is Exponent effective at helping clients with design analysis and test methods we are best known for figuring out "what happened" when something fails or develops a problem while in service. These projects can come in all sizes. Examples of Exponent's analysis in all these areas are listed below.

Bus Driver Safety

Following an attack on the driver of a bus, Exponent was asked to analyze the use of driver compartment shields as a possible means of preventing such incidents. Exponent conducted a survey of existing driver shields, reviewed the relevant literature, and observed their usage on buses throughout the country. We evaluated their effectiveness at preventing attacks on drivers, and analyzed other hazards that would be created or increased by the installation of such protection system. In addition, Exponent reviewed accident statistics to quantify the risks involved. Our findings showed that a driver shield would not have prevented such an attack, and that driver shields increase other risks to the driver and passengers.

Patent Infringement

The manufacturer of an automobile security system was concerned that another company’s design had infringed upon its patent. The primary issue had to do with the manner in which the internal parts of the security sensor moved. Exponent used high speed film to document and analyze the motions of the two different sensors. Our efforts proved that the second design did meet our client’s patent claims, and our client was pleased to be able to protect his design.

Suzuki Samurai

After a popular consumer magazine published an article suggesting that the Samurai easily rolls over in turns, Exponent was retained by Suzuki to conduct an extensive handling and rollover study. We compared the Samurai to other sport utility vehicles through a series of vehicle characterization (center of gravity height, moments of inertia, etc.) and handling tests, including the magazine's aggressive obstacle avoidance maneuver. We found that the Samurai performed better than several of its peers, which helped Suzuki to refute the magazine's claims.

Fuel Tank Mounting Strap

The manufacturer of a new light truck discovered a fuel tank retention problem during a pre-production frontal crash test. Exponent engineers worked with the manufacturer to design a sled test fixture and test matrix for evaluating design modifications to the tank mounting hardware. The greatest challenge associated with this project was the generation of a sled pulse representative of the crash test pulse, which contained a short-duration acceleration level well over 100g near the beginning of the pulse. The sled pulse was achieved by using aluminum honeycomb mounted on a structure that moved into our wire-bending decelerator only after failure of special shear pins tuned to the high g level. After exposing the most promising hardware modification to this representative pulse, the manufacturer felt confident proceeding to a full-scale crash test with the new design.

Conversion Van Restraint System

A van conversion company initially came to us to conduct FMVSS 208 frontal barrier crash testing on several of their new designs. However, when one of their designs failed to meet all of the occupant injury criteria, we were then enlisted to advise them on relocating the anchors and D-rings of their occupant restraint systems. This redesign effort led to successful completion of a repeat FMVSS 208 test as well as FMVSS 207/210 static seat and belt loading tests.

New Test Methods and Equipment

By developing new test protocols and equipment, Exponent recommended new SAE practices for occupant protection in heavy truck rollovers which were adopted industry-wide. An example of a unique system developed by Exponent is our head excursion machine, a tool for evaluating occupant head motion in rollover accidents. We also develop new test equipment when commercial products are unavailable. Over the years, in-house development of data acquisition systems for motorcycle, ATV, and automotive handling test applications have been key to the success of our test programs.

Component Evaluations

We have completed extensive evaluations of seat belt buckles for possible release during a crash. In lab studies, we have characterized the acceleration level required for a buckle to inertially release over a range of webbing tensions. We then look at the tension-acceleration relationship for the buckle during a crash test to learn whether it was close to releasing. Several pieces of test equipment were developed to support these evaluations.

In another project, we evaluated the performance of ABS brakes on a particular vehicle model. Data from 30 transducers was collected and analyzed for thousands of braking maneuvers on a variety of road surfaces, and under various conditions. The design of this multi-year test program was a collaborative effort between the Exponent project team and our client. Other components and subsystems we have studied have included transmissions, tires, gears, seat recliners, interior padding, exhaust systems, and a variety of occupant protection systems.

U-Bolt Failure Investigation

A municipal fleet vehicle catastrophically lost the rear axle on one of its trucks on a routine route. Exponent was asked to analyze the accident to determine why the axle separated from the truck. Examination of the fracture surface on the U-bolt indicated classic cyclic fatigue at the top dead center where the U-bolt contacts the top plate. The accident U-bolt revealed an inconsistent radius at the contact with the top plate, as compared to a new OEM replacement U-bolt. This change in contact surface resulted in an increase in bending stress. After detailed analysis, Exponent provided the client with recommended guidelines to use when replacing OEM parts with after-market hardware.

Engine Compartment Fires

After several reports of fires in a manufacturer’s popular model, Exponent was retained to identify the cause of the non-collision vehicle fires. We developed a test program that included measurement of exhaust system temperatures under various driving conditions. These conditions included controlled leakage of various engine compartment fluids onto or near the hot exhaust components. Our engineers developed a system for delivering controlled amounts of fluid when the driver could see that temperatures had achieved the targeted level. With a tiny video camera in the engine compartment and a monitor within his range of view, the driver could see whether the fluid ignited. A Halon fire-suppression system could then be activated by the driver to put out the fire. Having demonstrated that we could reproduce the fires that had been observed in the field, we then designed and tested various engine compartment modifications to reduce the incidence of fires.

Related Pages: Consulting Expertise, Vehicle Engineering

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