Standardized test customization

An automotive OEM requested support to perform vehicle measurements for power train and road noise on a 4WD chassis dynamometer. Five vehicles, OEM and competitive, were tested. Acoustic measurements as specified by the OEM were made at occupant positions within the vehicles for a variety of operating conditions, to measure power train and road noise. Measurements were taken on a 4WD NVH chassis dynamometer, using both smooth rolls and rough road shells to simulate on-road surface conditions. Subsequently, the data was used by the customer for benchmarking and target-setting purposes.

An automotive OEM needed help with vehicle level sound and vibration benchmarking of cooling fan noise and vehicle sensitivity to this. Operating noise and vibration measurements were done in a hemi-anechoic chamber with measurements made at driver interface locations and at key cooling fan system locations. FFT, order analysis, balancing techniques, and sound quality metrics were applied to characterize the cooling fan systems to set vehicle level targets. The developed targets were used to gauge the NVH performance of existing cooling fan systems and to set design guidelines for future programs. In addition to developing targets, we also optimized the OEM’s current cooling fan NVH test and data processing procedure.

A global provider of heating, ventilation and air-conditioning  (HVAC) systems chose us to provide test service support and perform vibration validation tests on their blower motors. Both operating and stationary vibration measurements were made at the customer’s US facility. Vibration levels at selected locations were measured to identify resonant conditions and compared to acceptance criteria. Imbalance, steady-state and torsional vibration validation was performed along with identifying resonances of the system . Outsourcing validation testing allowed the customer to relieve their overburdened staff from excessive work hours during the validation cycles while maintaining high quality in their validation testing.

As motor vehicles become quieter, some noises typically masked by an otherwise loud vehicle are now cause for new noise control applications. One such noise is fuel as it sloshes around inside the tank. A company that performs a variety of testing for auto parts manufacturers approached us to acquire and analyse fuel slosh noise. Acoustic and vibration data was acquired on a fuel tank while on a fuel slosh test sled. The data was analysed and compiled for the customer enabling them to maximize efficiency by focusing on test stand operation, and then propose improvements in the tank design to decrease the fuel slosh noise.

To support a vehicle development project, we were asked to collect structure-borne data for an automotive OEM to use in a source path contribution (SPC) analysis. The SPC analysis helps provide an overall image of the vehicle sensitivities and characterization in terms of noise and vibration. Vibrational acceleration per input force (A/F) frequency response functions were measured using a modally tuned impact hammer. The data we delivered to the customer was used in their SPC analysis to quantify the structure-borne paths from key vehicle acoustic and vibration sources to driver response locations.

An automotive OEM needed help in identifying potential cost reductions in relation to the interior treatments of vehicles for road noise. Operational noise measurements were conducted both on-road and on a chassis dynamometer with rough shells in a hemi-anechoic chamber.

Rough road shells on the dyno 

Objective 1/3-octave data and sound quality metrics were calculated for all cost-reduced interior package iterations to ensure road noise performance did not degrade. An optimized configuration was identified that maintained the vehicle’s NVH performance while saving US$1 million/year and 7 pounds of weight per vehicle.

Electric vehicles produce significantly less exterior noise than vehicles with internal combustion engines, which makes detectability of the vehicle more difficult for pedestrians, bicyclists, etc. The SAE J2889-1 draft standard provides a method of quantifying minimum exterior noise levels for electric vehicles. Using the SAE minimum noise test as a basis, a non-US transportation agency requested measurements on multiple electric vehicles. These acoustic measurements were made on an NVH chassis dynamometer in accordance with the SAE draft standard. The data was used to support the certification of these vehicles to meet standards held by the ransportation agency in terms of minimum exterior noise levels.

In addition, the agency wanted our help in acquiring pass-by test data from a number of indoor facilities to compare to data from outdoor facilities, to evaluate whether the draft standard can include an indoor measurement technique to minimize the influence of weather and site conditions.

A European supplier of vehicle exhaust systems needed to characterize the performance of its exhaust system in a US-market vehicle. To aid this, we conducted operational acoustic and vibration measurements of the exhaust with the vehicle on a chassis dynamometer in a hemi-anechoic chamber. Multiple microphone locations (interior/exterior), a binaural head and multiple accelerometers along the exhaust systems captured the NVH performance of the exhaust system while following customer standard specifications.

A global air conditioning, heating, and refrigeration systems manufacturer chose to outsource the measurement of sound power for qualification of their air handling units (AHU) for delivery to the final customer. Sound power measurements were made on the AHU at the customer’s facility in Canada, where they do not have a reverberation chamber. The sound intensity-based ISO 9614-2 specification was used for all measurements to quantify the sound power. We developed a process derived from standard procedures for measurements of noise from vehicle exhausts and intake orifices. This new process was applied to handle the challenge associated with making sound intensity measurements in the presence of a direct flow greater than 4 m/s (which is not allowed by the ISO spec). This alternative method for qualifying AHUs for sound power has saved the customer an excessive amount of time and shipping costs associated with measuring the AHU in the company’s reverberation chamber in their facility abroad.

A manufacturer of construction cranes needed help with sound power measurements and troubleshooting activities to qualify the crane assembly for delivery to the final customer. Standardized sound power measurements were conducted to quantify the source , and a beamforming array was used to localize the major acoustic sources for further refinement of the crane.

In this project, we performed modal testing on a large mining cutting wheel for a noise-control system designer. Using suspended modal shakers, vibration responses were measured at over 200 points on the cutting wheel to fully describe the vibrational mode shapes, frequencies, and damping. The results were delivered to the customer to correlate with FEA models.

An oil and gas equipment company requested help to perform validation tests on strings, sections of pipeline, designed to pump oil and gas along the sea floor and to the surface. Operational vibration measurements were performed at a supplier’s US facility. The string and a pump were submerged in over 30 meters of water. We supplied hermetically sealed accelerometers with integrated cables that could withstand being submerged. Vibration levels induced by the pump and the flow of liquid through the string were measured at 33 locations along the strings and compared to acceptance criteria curves. In addition to steady state validation testing, 72-hour endurance testing with hourly measurements was performed on the strings, to confirm the functionality of equipment prior to being placed in the field. 

An off-highway farm and construction vehicle manufacturer requested assistance in performing vehicle-level modal analysis. Vibration response data was acquired on the vehicle, using electromagnetic shakers (traditional modal analysis), and vehicle operating conditions (operational modal analysis).

The results were presented to the customer and used to correlate to low-frequency FEA models. An engineer from the vehicle manufacturer was involved in the testing and was trained on methods and analyses used.

A supplier of automotive driveline parts needed support for their NVH production test system for their facility in Germany. The project included the development of fault identification (pass/fail criteria) and the integration of our PULSE system in the customer’s end-of-line production test system. Operational noise and vibration measurements were conducted on the end-of-line test system. Types of analysis used included spectral, order, envelope,  1n octave and time domain. The new NVH production test system has increased the customer’s ability to prevent noise and vibration-related faults. In addition, the objective data obtained from faulty units have provided the customer with valuable information to assist in achieving quality improvements.