ASC’s capacitive accelerometers help optimise vehicle dynamics, component design, material selection and damping measures
Commercial vehicles for heavy use are typically put through their paces and adapted to conditions in their intended areas of operation. Like those from a leading global manufacturer based in Germany, who has been leveraging ASC sensor technology for nearly two decades
Whether on the test track, on test benches or in real-world use: ASC’s capacitive accelerometers help optimise vehicle dynamics, component design, material selection and damping measures, as well as the overall operational stability and service life of commercial vehicles.
SIMULATING GLOBAL OPERATING CONDITIONS
“Apt sensor technology plays an essential role in accurate load detection for the tuning and quality control of our vehicles”, states one of the ASC clients’ test engineers with over 15 years of experience in the field of operational stability. Each vehicle prototype undergoes a rigorous testing programme. “It starts on our test track for measuring vibration behaviours. Here we can simulate a wide variety of conditions to reflect those around the world.”
The vehicle is driven over a wide range of diverse road types, surfaces and conditions. This includes inclines, declines, curves and obstacles such as speed bumps, railroad crossings with interlocking tracks, potholes, cobblestones or wet and slippery road sections. These sequences of obstacles and manoeuvres are analysed and evaluated for maximum permissible stress loads.
Vibration loads are recorded at critical points across the vehicle. The aim is both to check whether the actual loads are within the scope of calculations and to obtain reference data for subsequent operational load reproduction tests on the test bench. Facilitating this, inertial sensors from ASC record exact accelerations and directions, rotational movements, maximum speeds and reversal points. From that, further relevant forces and complex mechanical stress loads are calculated, which the components get exposed to intensively on the test bench later, over extended periods of time.
ASC 5525MF: THE ALL-ROUNDER
“The sensors we use must be extremely robust and versatile”, states the engineer. Triaxial capacitive accelerometers of the ASC 5525MF (Medium Frequency) range lend themselves specially to this. With measuring ranges from ±2 to ±200g and a wide frequency response from 0 to 7kHz (±3 dB), they are particularly suitable for capturing low and medium frequencies.
As typical driving manoeuvres such as accelerating, braking, coupling, negotiating bends, overcoming long bumps, railroad crossings, thresholds, curbs or dips and much more often require measuring ranges up to a maximum of 100Hz. “Without the ability to accurately capture low frequency responses, we wouldn’t be able to replicate real-world conditions and loads during test drives.”
The robust ASC 5525MF design ensures strong resistance to repeated shock loads of up to 6,000g. It comes embedded in a reliable stainless-steel housing of protection class IP 67. All this and its flexible installation options make the analogue accelerometer ideal for accurate data acquisition under highly variable, sometimes unexpected and adverse terrain, environmental and climatic conditions.
FINE-TUNING WITH CAPACITIVE MEASUREMENT TECHNOLOGY
After the test drives have been completed, the commercial vehicles undergo a second round of thorough testing on test benches. To simulate continuous loads over their entire service life, they get “shaken” for weeks on servo-hydraulic test rigs that replicate those movements and loads as closely as possible that will impact the vehicle in real-world use.
“In so-called operational load reproduction tests, innovative sensors are used to replicate the actual operating profile”, explains the head of the manufacturer’s measurement and calibration laboratory. “The overall stress on individual components and the entire vehicle then gets extrapolated from these test series to thousands of additional miles.” Which saves the producer a lot of time and wear, personnel, fuel and other material costs.
These reproduction tests can take up to 400 hours or more, in automated 24/7 mode. Based on the insights, the material strength of critical components is optimised and the effectiveness of suitable measures to reduce the impact of stress and increase service life – such as vibration damping measures – gets evaluated and adjusted.
INERTIAL SENSORS OF PRECISION AND STABILITY
The accurate measurement of linear acceleration is critical for the valid recording and evaluation of stress events. “We need precise accelerometers that are also easy to handle and install”, says the measurement expert. “They must cover wide frequency ranges, be robust and deliver stable results over the long term. Water, dust or dirt must not affect these sensors.”
ASC 5525MF triaxial accelerometers are particularly suited for these intensive testing series. Their compact design facilitates quick installation and removal – a fundamental advantage in NVH (noise, vibration, harshness) and test bench applications.
Based on proven MEMS technology and the capacitive measurement principle, they enable the detection of even the smallest acceleration forces in three degrees of freedom across a wide frequency response. This ensures maximum accuracy and stable long-term results. ASC 5525MF sensors are, therefore, popular for use in test settings, vehicle and road surface monitoring, yet also in resonance and vibration tests in aviation, for another example.
Words by Oliver Stohlman on behalf of ASC Sensors. www.asc-sensors.de
