Automotive Research, Test & Measurement
The world of NVH (Noise, Vibration & Harshness) testing is the very cornerstone of automotive development. The need to develop smooth, quiet and reliable vehicles requires a detailed understanding and mastery of vibration and structural analysis, to this end the Automotive industry uses accelerometers in the widest
range of applications. DJB offers solutions for almost every conceivable application, but one in particular remains unique to DJB and market leading for those involved in the most extreme conditions of turbo or
exhaust test and development. The A/133 IEPE and A/33 charge output water cooled accelerometers were developed by DJB in association with several major Automotive customers for the testing and measurement of exhaust and turbo charger vibration. Extreme temperatures exceeding 900°C are not uncommon on turbo chargers and measuring vibration at these temperatures is extremely difficult and although non-contact vibration measurement is possible, it is also extremely expensive. The A/33 charge based triaxial accelerometer was originally developed in 1997 and was followed in 2005 with the IEPE version A/133. Both capable of measuring vibration on a product with a surface temperature up to 900°C using a simple water cooling system with a flow rate of approximately 0.5 litre per minute, the accelerometers are offered in triaxial and uniaxial configurations.
Typical accelerometers used:
NVH and Modal analysis
A major US Automotive OEM approached DJB for a triaxial accelerometer for use in testing exhaust vibration on vehicles in full operational conditions, i.e high temperature and road use. Their data acquisition and analysis system had the facility to provide the constant current supply to operate an IEPE accelerometer, so DJB specified the A/133 variant. As the picture shows, the accelerometers were installed in a number of locations on a new exhaust development. With a single bolt mounting through the centre of the accelerometer body they are simple to install in what can be a confined space. Supplied with cooling water via a windscreen washer pump, the accelerometer cables and cooling pipes were protected by over braiding to avoid damage under the vehicles during road tests, these were routed back to the instrumentation and pump/water supply within the vehicles boot. Cables were also supplied by DJB and were made to suit the customers’ installation requirements. Over the many years of field use the A/133 and A/33 accelerometers have proven themselves as extremely rugged devices that can be used in harsh conditions for many years. On the rare occasion damage occurs they have the benefit of being fully repairable, each axis insert can be removed and replaced.
• Konic Shear® for long term cross axis stability
• High temperature
• High reliability
• Proven track record of performance
• Integral stainless steel cables or connectors
• Low cost range available