Optimized Vibration Analysis for Brakes
Brake noise is one of the most common customer complaints in the automotive industry. Although brake noise is primarily a subjective annoyance that results in high warranty repair costs for manufacturers, unwanted dynamic behavior of the brake system can also impair performance and durability. Manufacturers work with suppliers and sub-suppliers to develop new, optimized brake systems or resolve issues with existing designs.
Understanding Brake Squeal
The dynamic behavior of the brake system is crucial to the overall assessment of braking function and perceived vehicle performance. Since occupant comfort is a major priority in vehicle development, manufacturers aim to reduce warranty repair costs and achieve better noise, vibration, and harshness (NVH) performance by eliminating brake squeal to gain market share. Acoustic comfort is a key purchasing consideration for potential buyers, particularly in the premium vehicle segment. Moreover, brake noise becomes more noticeable as other sources of noise, such as engine noise, are eliminated—for example, through the use of modern electric powertrains.
Brake squeal is caused by friction between the brake disc and brake pads and the resulting excitation of vibration modes at frequencies perceived as unpleasant by the human ear. In brake development, finite element models are used to identify such modes and suppress their occurrence by appropriately modifying the brake geometry or implementing other design measures. These simulation models require validation measurements to verify the model parameters and the resulting responses. With SMART Lab, simulation points can be imported directly as measurement points, enabling precise validation not only at a large number of points, but also at the correct measurement locations.
Analyzing Brake Dynamics Under Realistic Conditions
The SMART Scan+ scanning laser Doppler vibrometer from Optomet enables non-contact measurement and analysis of vibrations occurring on the surfaces of the brake disc, pad, and caliper, as well as their visualization in 3D animations. This allows finite element model calculations to be accurately compared with and validated against actual vibration behavior.
Brake dynamics can be investigated either by exciting the brake with a modal hammer or by measuring brake vibrations under operating conditions. The first method captures all modes of the brake system, but does not account for the influence of mounts and couplings on vibration behavior or for the characteristic modes experienced by the driver in the actual vehicle. The second method uses scanning laser technology on brake test benches to optimize vibration analysis of the brake disc, pad, and caliper system under conditions that are as realistic as possible. However, the deliberate excitation of brake squeal is generally not readily repeatable. Optomet scanning laser vibrometers are designed to measure only when brake squeal occurs, saving time and improving testing efficiency. Optomet multi-point systems can also capture numerous measurement points simultaneously—with SMART Multi-Fiber, even during the brief squeal event itself.
SWIR Technology for Rotating Brake Discs
The Optomet SWIR laser vibrometer technology is ideally suited for measuring brake systems and automotive components. The key advantage of the Optomet solution over conventional HeNe-based systems becomes particularly evident when measuring rotating brake discs on a test bench. Back-to-back tests of SWIR and HeNe vibrometers have shown that excessive optical signal noise prevents HeNe systems from delivering measurement data with sufficient quality or signal-to-noise ratio. The resonances under investigation are lost in the noise. By contrast, Optomet SWIR laser vibrometer technology delivers a dramatic improvement, providing data in these applications with noise levels 40 dB to 50 dB below the resonance peaks below.
Vibration measurement in research, development and industry – Optomet offers the right solution for your requirements.
Contact