Brake Squeal Dynamometer

Brake-Squeal Dynamometer

Sponsors: Integrated Acoustics Laboratory, General Motors, Trelleborg Automotive

Students: Ryan Rye, Aaron Graf

Advisor: Dr. Cunefare

The objective of this project is to develop a brake-squeal dynamometer facility for investigation of brake-squeal phenomena. Additional project details may be found here. The project incorporates a 40 Hp speed-controlled electrical motor, a Polytec scanning laser vibrometer, and an acoustic intensity probe system. Data acquisition and control are performed by LabView through an NI thermocouple card and an 8 channel Microstar Laboratories high-speed data acquisition card.

Click on the images below for more information.

Instrumentation

The business end of the dynamometer

Motor and speed reducer

Laser scan

Intensity scan

DR. Cunefare's HOME PAGE IAL Home Page IAL Projects Page

Instrumentation system

Polytec PSV 200 scanning laser vibrometer with Fastscan capability. Triggered off mic signal above Lp threshold
National Instruments PCI 6713 Card = 8 analog outputs, 8 digital I/O, and 2 counter/timers
National Instruments PCI 4351 Card = Thermocouple inputs for pad temperature and slow sample rate analog inputs for static hydraulic pressure
Microstar Labs iDSC 816 Analog Input Card = 8 analog inputs with separate configurable digital filters, max sampling rate of 51.2 kHz per channel
Sensotec S-TJE static pressure transducer and PCB 101AO5 dynamic pressure transducer
Parker Motion Control linear actuator for applying and maintaining brake pressure
Larson-Davis intensity probe

View of the brake caliper and rotor, input shaft, speed-reducer, and hydraulics.

View of the 40 Hp variable speed motor and speed reducer

Surface normal velocity scanned by PSV 200 at 7.1 kHz. Note that we do confirm what appear to be antinodes along the circumference of the rotor. The PSV only recorded accelerations in the 7.05-7.15 kHz range for this picture. Click here for more vibrometer scans.

Sound intensity scan of squealing disc brake at 7.1 kHz. Highest sound intensity levels (dB re 1 pW/m^2) are clearly located near the top and bottom regions of the pad. X and Y axes are in cm. The measurement plane is located approximately 8.5 cm away from the rotor surface (as close as the probe could be positioned without interfering with the rotating studs on the wheel hub).

1. Exposed rotor surface during no squeal condition (left figure) and squeal condition (right figure).

Note areas of high acceleration magnitude (red and white areas) located along circumference of the rotor--diagonally

across from the top and bottom of the caliper.

2. Exposed caliper surface during no squeal condition (left figure) and squeal condition (right figure).

Areas of larger acceleration magnitude (red) have developed at the top and bottom of the caliper.

3. Top tip of brake pad during no squeal condition (left figure) and squeal condition (right figure).

At the top tip of the pad, the selected point's acceleration magnitude increased from 30.9 to 1314 m/s^2 during squeal.