Abstract:The performance of automotive brake discs is crucial for driving safety, as they are subjected to complex dynamic loads during braking, leading to vibration and noise issues. Modal testing is essential for understanding the vibration characteristics of brake discs, evaluating structural design rationality, and predicting potential vibration failures. This paper presents the application of the Sunnyinnovation Scanning Laser Vibrometer LV-SC400 in brake disc modal testing. The LV-SC400, with its frequency bandwidth of DC-3MHz, along with the QuickSV scanning acquisition software and QuickMA analysis software, provides a comprehensive solution for obtaining modal parameters such as natural frequency and modal shape. The experimental setup involves suspending and fixing the brake disc, using an automatic impact hammer for excitation, and analyzing the data with the QuickMA software. The results demonstrate the effectiveness of the LV-SC400 in optimizing brake disc structure, reducing vibration and noise, and improving the reliability and comfort of automotive braking systems. Future applications of the LV-SC400 in other fields such as aerospace, civil engineering, and industrial machinery are also discussed.Introduction:The automotive industry is increasingly focusing on the safety and comfort of vehicles. The brake disc, as a critical component of the braking system, plays a significant role in ensuring driving safety. However, during braking, the brake disc is subjected to complex dynamic loads, which can lead to vibration and noise problems. Modal testing is a powerful tool for understanding the vibration characteristics of brake discs, evaluating the rationality of their structural design, and predicting potential vibration failures. This paper explores the application of the Sunnyinnovation Scanning Laser Vibrometer LV-SC400 in brake disc modal testing, highlighting its hardware and software capabilities, and discussing its future applications.Experimental Setup:The experimental setup for brake disc modal testing involves the following components:Sunnyinnovation Scanning Laser Vibrometer LV-SC400: This device has a frequency bandwidth of DC-3MHz, making it suitable for capturing high-frequency vibrations.Automatic Impact Hammer: Used for impact excitation of the brake disc.QuickSV Scanning Acquisition Software:Collects the impact data from the LV-SC400.The QuickSV software shows as below.QuickMA Analysis Software: Analyzes the collected data to obtain modal parameters such as natural frequency and modal shape.The QuickMA software shows as below.The brake disc is suspended and fixed, and the automatic impact hammer is used to excite the disc. The LV-SC400 captures the vibration data, which is then analyzed using the QuickMA software.Results and Discussion:The LV-SC400, combined with the QuickSV and QuickMA software, provides accurate and reliable modal parameters for the brake disc. The natural frequency and modal shape obtained from the analysis are crucial for understanding the vibration characteristics of the brake disc. These parameters help engineers optimize the brake disc structure, reduce vibration and noise, and improve the reliability and comfort of the automotive braking system.Future Applications:The LV-SC400 has potential applications beyond automotive brake disc testing. In the aerospace industry, it can be used for modal testing of aircraft components. In civil engineering, it can be applied to the vibration analysis of bridges and buildings. In industrial machinery, it can help in the design and optimization of machinery components to reduce vibration and noise.Conclusion:The Sunnyinnovation Scanning Laser Vibrometer LV-SC400, along with the QuickSV and QuickMA software, provides a comprehensive solution for brake disc modal testing. Its high-frequency bandwidth and accurate data analysis capabilities make it an essential tool for optimizing brake disc structure and improving automotive braking system performance. The future applications of the LV-SC400 in other fields such as aerospace, civil engineering, and industrial machinery are promising, making it a versatile and valuable tool for vibration analysis.

Optical System PrincipleThe core of the Sunnyinnovation laser vibrometer is a high-precision laser interferometer and a signal processor. The polarized light (with a frequency of F0) emitted by the laser in the high-precision laser interferometer is split into two beams by a beam splitter. One beam serves as the measuring light, and the other serves as the reference light. The reference light undergoes a certain frequency shift (F) through an acousto-optic modulator. The measuring light is focused onto the surface of the measured object. The vibration of the object causes a Doppler frequency shift (f = 2v/λ) of the measuring light. The system collects the reflected light and combines it with the reference light on the sensor. In this way, the two beams interfere on the surface of the sensor. The frequency of the interference signal is F0 + F + f, which carries the vibration information of the measured object. The signal processor then converts the frequency signal into the velocity and displacement signals of the object's vibration.Doppler effectDuring the propagation of a wave, its frequency changes with the relative motion between the wave source and the observer. When light shines on the surface of a moving object, for a light detector, the motion of the object causes a change in the frequency of the light scattered from its surface. This frequency change value is related to the velocity and direction of the object's motion, the wavelength, and the direction of the incident light. If the values of the latter parameters are known, the velocity of the moving object can be obtained by measuring the frequency change of the scattered light.Principle of Optical Heterodyne InterferenceOptical heterodyne interference occurs when two coherent light beams with different frequencies are simultaneously projected onto the photosensitive surface of a photodetector and interfere with each other. Then, through the square-law effect of photoelectric conversion, the frequency difference between them is obtained. This frequency difference is the required Doppler frequency shift. The remaining frequency information that is close to or higher than the optical wave frequency is filtered out because it exceeds the frequency response range of the light detector.Sunnyinnovation Laser Doppler Vibrometer Series

Project BackgroundIn applied mechanics and many engineering fields, the measurement of displacement fields, strain fields, and stress fields is of great significance. With the continuous improvement of requirements for testing environments and testing accuracy, traditional contact - type measurement methods at finite points face significant limitations. The most commonly used contact - type strain measurement methods, such as strain gauges and piezoelectric sensors, can only obtain strain data at discrete points. For lightweight structures, they will also introduce additional mass effects. Non - contact measurement methods, such as photoelasticity, X - ray diffraction, digital image correlation, and holographic interferometry, have applications in specific scenarios. The development of laser Doppler vibration measurement technology provides a new solution for non - contact full - field dynamic stress and strain measurement. This article will use the Sunnyinnovation Scanning Laser Doppler Vibrometer to measure surface vibration information and combine it with post - processing algorithms to achieve high - resolution dynamic surface strain and stress evaluation.Test ObjectThe beam is a simple structure. Its advantage is that the exact stress - strain distribution can be obtained through theoretical calculations, and its performance is easy to describe from the perspectives of experiments and models. In this test, an aluminum symmetric cantilever beam of model 6061 is used as the test object. A shaker is used to apply a sinusoidal excitation load of 10Hz - 10kHz to the fixed end of the beam.Test Object Test Equipment LV - SC400 Laser Scanning VibrometerSunnyinnovation optical intelligence Laser Scanning Vibrometer LV-SC400 can measure the vibration of the structure surface through high - speed scanning galvanometers, thereby obtaining real high - resolution displacement and deformation data. Then, the corresponding strain can be calculated through the Sunnyinnovation Modal Analysis Software.Test ResultsThe test area is 40mm in the horizontal direction and 70mm in the vertical direction. The measuring points are arranged in a 6×31 pattern, with a total of 186 measuring points. The displacement information of each measuring point can be quickly obtained through scanning. Layout of measuring pointsAfter measuring the displacement data of the measuring points at a certain moment, the full - field strain data and stress data at the current moment can be obtained through the stress - strain post - processing software. Strain pictureApplication ProspectsBy using a scanning laser vibrometer to measure the vibration of a structure and conduct stress - strain analysis, the areas with the largest strain and stress in the structure can be determined. Thus, it is possible to predict the positions in the structure that are most likely to experience failures or serious damage due to resonance. The dynamic strain distribution can also provide high - precision measurement data for fatigue tests, which is of great significance for improving structural design and ensuring the safety and reliability of structures.About SunnyInnovation Optical Intelligence Corporation LimitedEstablished in 2008 as a technology subsidiary of Sunny Optical Corporation Ltd in Yuyao, Zhejiang, China, SunnyInnovation is engaged in the development of laser Doppler vibrometers for vibration measurement and technical service in solutions for product design and optimization concerning the vibration.  SunnyInnova has faithfully served China’s universities, research institutes, industrial R&D centers, and infrastructure operators with sophisticated and competitive laser vibrometers for vibration measurement with mechanical, civil, transportation, medical, energy, aerospace, biological, healthcare, sports, and many structures and objects.  According to leading market research and advisory firms, SunnyInnova has remained the leading brand in China’s overall laser Doppler vibrometer product market for 10 consecutive years (2014-2024) in terms of products and unit shipments. In recent years, SunnyInnova has focused on the development of advanced vibrometers for scanning, MEMS, and mode shape generation to support the demands from research and product development efforts related to vibration measurement, control, utilization, and optimization with broad industries and technical services. The laser vibrometer products won the First Prize of Ningbo Science and Technology Awards and the Second Prize of Zhejiang Science and Technology Advancement Awards.  SunnyInnova has also been collaborating with Tsinghua University, Peking University, Zhejiang University, and many institutions on important research projects with the utilization of laser vibrometers for measurement and analysis under special circumstances using creative functions, further demonstrating SunnyInnova's vibrometer products and solutions have gained recognition in the key sectors of market. For further information, please visit www.sunnyinnova-ldv.com. 

What is modal analysis?Modal analysis is the dynamic characteristic of object structure under vibration excitation. Structural engineers can extract modal parameters (dynamic characteristics) of a structure through modal analysis. Modal parameters can help structural engineers understand the response of a structure to environmental conditions for design validation.The modal analysis of the optical discWith the increase of the data transmission rate of the optical disc drive, the speed of the spindle motor also increases. Today, it has reached about 12,000 revolutions per minute, and if the disc has a little eccentric mass, the vibration caused by the unbalance will be intensified, causing great difficulties for the focus and circulation of the optical head. The modal analysis of the optical disc is carried out to obtain its natural frequency and modal changes, which can be used as a theoretical basis for evaluating the characteristics of the optical disc and to determine whether the strength of the optical disc meets the design requirements.Optical disc modal test analysis challenge1) The quality of the disc is small, and the contact sensor has a large impact on the test of the disc;2) The mode mode needs to collect multi-point data from the disc, and the traditional method needs to be measured several times, which is low efficiency;3) Optical disc modal analysis is in urgent need of an efficient measurement method without mass addition.Optical disc modal test analysis solutionScanning laser vibrometer LV-SC400 & modal test systemSunnyinnovtion optical intelligence laser Doppler vibrometer LV-SC400 can achieve the amplitude resolution of nanometer and picmeter-level. The system uses laser as a means of detection, has no additional mass effect, and can be measured on extremely small and lightweight structures.System features: The galvanometer can achieve deflection Angle change of 40°×50°. The camera can achieve 30x optical zoom and 12x digital zoom. Velocity resolution is better than 0.01μm/√Hz, displacement resolution is better than 0.31pm.Test environment construction1) The signal generator generates the sweep frequency signal, and the optical disc vibration is stimulated by the piezoelectric plate.2) The scanning laser vibrometer equipment is built3) The model is laid out on the software, and the laser point is scanned point by point and the data is collectedData analysis1) The software can be time domain analysis, spectrum analysis, frequency response amplitude analysis and frequency response phase analysis2) Modal analysis is carried out by modal algorithm, and the frequency and damping ratio are obtainedMode display50Hz105Hz265Hz487HzTest conclusionThe natural frequency and modal modes of the optical disc are obtained by scanning laser vibrometer, which provides a favorable theoretical basis for evaluating the characteristics of the optical disc and can be used to interpret the strength of the optical disc. Under the high-speed operation of the disc, the natural frequency is avoided, and the structure is optimized under a specific frequency. The "Modal artifact" can perform modal testing quickly and efficiently, which has a great advantage over traditional chip sensors. "Modal artifact" not only can be used for optical disk modal testing, but also can be widely used in various structural analysis, ultrasonic piezoelectric testing, and research of new materials. About SunnyInnovation Optical Intelligence Corporation LimitedEstablished in 2008 as a technology subsidiary of Sunny Optical Corporation Ltd in Yuyao, Zhejiang, China, SunnyInnovation is engaged in the development of laser Doppler vibrometers for vibration measurement and technical service in solutions for product design and optimization concerning the vibration.  SunnyInnova has faithfully served China’s universities, research institutes, industrial R&D centers, and infrastructure operators with sophisticated and competitive laser vibrometers for vibration measurement with mechanical, civil, transportation, medical, energy, aerospace, biological, healthcare, sports, and many structures and objects.  According to leading market research and advisory firms, SunnyInnova has remained the leading brand in China’s overall laser Doppler vibrometer product market for 10 consecutive years (2014-2024) in terms of products and unit shipments. In recent years, SunnyInnova has focused on the development of advanced vibrometers for scanning, MEMS, and mode shape generation to support the demands from research and product development efforts related to vibration measurement, control, utilization, and optimization with broad industries and technical services. The laser vibrometer products won the First Prize of Ningbo Science and Technology Awards and the Second Prize of Zhejiang Science and Technology Advancement Awards.  SunnyInnova has also been collaborating with Tsinghua University, Peking University, Zhejiang University, and many institutions on important research projects with the utilization of laser vibrometers for measurement and analysis under special circumstances using creative functions, further demonstrating SunnyInnova's vibrometer products and solutions have gained recognition in the key sectors of market. For further information, please visit www.sunnyinnova-ldv.com.