Accelerometers, Load Cells, Force Sensors, and Signal Conditioners
Due to the increasing competitive pressure in the global Automotive Industry, vehicle development schedules have decreased from 4-5 years a decade ago, to less than 2 years today. This has allowed manufacturers to react more judiciously to changing consumer demands, market conditions, and legislative requirements. The challenge for the vehicle development community is to meet these condensed timelines without negatively affecting quality and performance attributes such as warranty, fuel economy, crash worthiness, NVH (Noise, Vibration, and Harshness), and driver comfort. At the most fundamental core of any development program is vehicle and component durability testing. The success of a durability program lies in its ability to replicate the summation of all major inputs a vehicle would likely see in its operating environment in the shortest time possible. A poorly executed durability program can cost a manufacturer millions in warranty costs, reduced sales, and a loss of customer loyalty. In order to expedite durability testing without sacrificing due diligence, many vehicle manufacturers have adopted virtual development methods that are coupled with traditional durability testing. With these virtual techniques, however, comes more scrutiny on the reliability, repeatability, and accuracy of the limited physical tests.
Robustness, flexibility, reliability and fidelity of sensors and instrumentation are compulsory for any successful durability test program. It is rarely feasible for a complete durability program, or a significant portion of it, to be repeated due to faulty equipment or sensors. PCB® designs sensors with these requirements in mind to support compressed product development time and to ensure that a vehicle, system, and component is measured successfully and accurately the first time. A typical durability test program consists of the following key test elements:
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Full Vehicle Durability
Road load tests measure the transient and steady state inputs of a vehicle as it operates over a road surface in the intended market region or over a replicated drive profile on a test track. The road load test accounts for vehicle and driving parameters such as mass, inertia, air & rolling resistance, road characteristics, engine loads, and vehicle speed.
Data gathered from Road Load Data Acquisition (RLDA) is processed and analyzed and used for control of a powertrain/chassis dynamometer in the case of a powertrain durability program; or multi-axis hydraulic shakers for a vehicle structural durability program. Simulated durability programs are separated as it becomes almost impossible to control both load profiles. Full vehicle durability can be performed in its entirety, with both powertrain and chassis induced loads, on a test track with a drive profile that replicates the road surface and vehicle speed necessary for the intended geographical region. While vehicle durability testing on a test track offers the most realistic load cases, it often takes longer to complete and is dependant on the current ambient conditions only, not the specific conditions that are necessary. Simulated powertrain or vehicle structural durability, on the other hand, offers more repeatable test outcomes in an expeditious manner.
Many vehicle systems and components experience complex static, dynamic, and thermal loading conditions when operated. Data gathered from road load or vehicle durability results are used to simulate these load conditions in a lab where forces and ambient temperatures acting on the test subject can be controlled. Climatic chambers are used for specific control of ambient conditions including temperature and humidity while multi-axis shaker systems can control up to three axis of motion simultaneously and independently. For controlled component durability testing, where control of the inputs and the response of the test object are crucial, PCB® offers robust quartz accelerometers with high sensitivity and excellent resolution that are well-suited for this demanding application. For tests requiring tight control of inputs over large temperature variations, PCB® Series 339A low temperature coefficient triaxial ICP® accelerometers, ensure accurate representation.