制动钳工作过程的DIC测量 Brake Caliper Meets High-Speed Digital Image Correlation
了解车辆制动系统中每个部件的动态行为可以极大地提高系统性能和寿命。 但是，由于硬制动事件的动态性质，要使用传统方法测量任何部件的位移和应变都极具挑战性。 而传统的测量方法通常还需要与试件接触，且只能产生单一位置的数据。
Understanding the dynamic behavior of each component in a vehicle braking system can vastly improve performance and longevity. However, measuring displacements and strains using traditional methods can be extremely challenging on any component due to the dynamic nature of a hard-braking event. Also, traditional measurement methods typically require contact with the specimen and only produce data at one location.
数字图像相关技术（DIC）是一种出色的测量工具，既可用于测量3D中的全场表面位移、应变和振动频率，且无需与试样接触。 在此案例中，VIC-3D HS FFT系统捕获硬制动事件过程中制动钳的图像并进行后期处理。 DIC只需将简单的散斑图案制作到试件上即可。 该试验使用水溶性喷漆，在测试后，用湿海绵即可将其轻松擦除而不影响试件外观和机械性能。
Digital image correlation (DIC) is an excellent tool for measuring full-field surface displacements, strains, and vibration frequencies in 3D without requiring any contact with the sample. In this example, the VIC-3D HS FFT system was used to capture images and post-process results of a brake caliper during a hard braking event. Applying a simple speckle pattern to the test specimen is all that is required for DIC. Here, a water-soluble spray paint was used, which was easily removed with a wet sponge after the test.
测试数据为车辆从时速40 英里降速到0 的过程中，卡钳在制动负载下的变形和应变。另外，在施加制动力之后，系统识别并测量了卡钳的工作变形(ODS)和频率。 该系统还可以用于各种准静态和其他动态应用，以测量冲击响应、碰撞测试中的部件变形、高应变率测试等等。
Deformation and strain on the caliper were measured under a load produced by braking from 40 mph to 0 mph. Additionally, the operational deflection shapes (ODS) and frequencies were identified and measured after braking was applied. The system can also be used for a wide range of quasi-static and other dynamic applications for measuring impact responses, component deformation from crash testing, high-strain rate testing, and much more.
从VIC-3D HS FFT系统生成的数据也可以导出以验证FEA模型，从而加速产品的最终设计并将其以前所未有的速度推向市场。 请联系我们的销售团队，以探索VIC-3D数字图像相关测量系统如何革新您的设计和测试程序！
The data produced from the VIC-3D HS FFT system can also be exported for validating FEA models, which will ultimately accelerate your product’s final design and bring it to market faster than ever. Contact our sales team to explore how the VIC-3D digital image correlation system can revolutionize your design and testing program!
排气歧管试验案例 Manifold Testing Example
The engineers at Cummins design and test their engines to withstand real-world conditions, ranging from military deployments to heavy-duty industrial sites. Cummins engineers want to know exactly how their parts are deforming under the combination of thermal and mechanical loads. This means they have the need to perform their tests with the engines running… hot!
图示Figure 1. 发动机排气歧管照片Photograph of engine manifold.
Because of the complex strain fields produced under these conditions, conventional strain gages cannot satisfy Cummins’ requirements. FEA simulations are also limited, due to the uncertain boundary conditions and complexity of the loading. With the VIC-3D™ System, Cummins engineers were able to obtain detailed three-dimensional strain measurements. These measurements are made under real loading conditions while the engine is running. In addition, the VIC-3D™ System is easy to set up and can measure both small parts and large assemblies. Care must be taken when imaging hot specimens with DIC, because heat waves can severely bias data. However, a simple solution to this potential bias is to utilize a fan to move and mix the hot and cool air, which is easily integrated.
康明斯高级研究工程师 Paul Gloeckner 解释了 VIC-3D 系统的实用性：“这一工具允许我们做以前不可能做到的测量。它还使我们大大减少这些测试所需的时间。”
Paul Gloeckner, senior research engineer at Cummins, explains the usefulness of the VIC-3D™ System as follows: “This tool allows us to make measurements that were previously not possible. It has also allowed us to considerably reduce the time required for these tests.”
图示Figure 2. VIC-3D 排气歧管应变数据strain data of manifold.
Correlated Solutions now supports select IR cameras, which can be integrated with any quasi-static VIC-3D system. Temperature data from IR cameras can now be calibrated and synchronized with the DIC system, producing very robust and more informative data.
* 数据由康明斯发动机提供 Data Courtesy of Cummins
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制动盘ODS工作变形测量 Measuring Operational Deflection Shapes of a Brake Rotor
图2显示了在120.0Hz处的一阶工作变形。 全场云图显示了该频率下的离面运动和相位信息。 如以下云图与曲线所示，在120Hz一阶振型下测得的平均振幅为84纳米。
Figure 2 shows the first operational deflection shape at ~120.0Hz. The full-field plots show the out-of-plane motion and phase at this frequency. An average amplitude of 84 nanometers was measured as the ODS at ~120Hz, as seen in the plots and graphs below.
离面运动如以下的3D动画处理中所示，更好地显示最大值、最小值和ODS工作变形的节点。 对应该频率下，制动盘的总振幅约为+/- 268纳米。
The out-of-plane motion is animated in 3D below to better show the maximum values, the minimum values, and the nodes of the operational deflection shape. At this frequency, the brake rotor experienced a total out-of-plane deformation of approximately +/- 268 nanometers.
图4更详细地显示了在932.7Hz处的二阶工作变形。 以下云图的左图和右图分别显示了该频率下的振幅和相位信息。 如左图所示，该ODS的平均振幅为183纳米。
Figure 4 shows the second operational deflection shape at 932.7Hz in greater detail. The full-field left and right plots show the out-of-plane shape and phase respectively at this frequency. An average amplitude of 183 nanometers was measured for this ODS, as seen in the left graph.
离面运动如以下的3D动画处理中所示，更好地显示最大值、最小值和ODS工作变形的节点。 对应该频率下，制动盘的总振幅约为+/- 375纳米。
The out-of-plane motion is animated in 3D below to better show the maximum values, the minimum values, and the nodes of the operational deflection shape. At this frequency, the brake rotor experienced a total out-of-plane deformation of approximately +/- 375 nanometers.
Figure 5. Animated 3D view of the brake rotor at 932.7Hz
Figure 6 shows the third operational deflection shape at at 2,087.4Hz. The full-field left and right plots show the out-of-plane motion and phase respectively at this frequency. An average amplitude of only 25 nanometers was measured for this ODS, as seen in the left graph.
The out-of-plane motion is animated in 3D below to better show the maximum values, the minimum values, and the nodes of the operational deflection shape. At this frequency, the brake rotor’s ODS was measured to have an out-of-plane amplitude of +/- 64 nanometers as shown in the animation below.
Figure 7. Animated 3D view of the brake rotor at 2087.4Hz
对于该测试，测得的离面振幅噪声信号约为4纳米，这非常理想。该系统还在频域数据中显示出卓越的动态范围。 为了进行更深入的分析，可以将平均测量值与参考点、提取点进行比较。 为了轻松进行有限元分析和模态分析验证，可以通过动画、.csv和其他各种格式导出全局的3D数据。
For this test, the out-of-plane amplitude noise signal was measured to be approximately 4 nanometers, which is excellent. The system also shows excellent dynamic range in the frequency domain. For a more in-depth analysis, the average measurements can be compared to reference points and point extractions. For easy finite element analysis and modal analysis validation, the full-field 3D data can be exported in the form of animations, .csv’s, and other various formats.
该案例表明，VIC-3D HS-FFT系统可以实现幅度小至64纳米、频率超过2,000Hz的振动测量，每个时间步可以获取多达百万个数据点。 与传统和激光测量技术相比，这种非接触式全场测量工具可在更短的时间内提供更多数据且无需定频激励。 VIC-3D HS-FFT系统可分析和呈现任何瞬态事件中一次激发后在不同频率下的多阶ODS工作变形信息。 此外，系统同步处理获取的高价值的全场3D应变和位移数据可与振动数据一起显示。
This example shows that measurements with amplitudes as small as 64 nanometers and frequencies over 2,000Hz with up to 1 million data points at every time step are achievable. Compared to traditional and laser measurement techniques, this non-contact full-field measurement tool provides more data in less time. The VIC-3D HS FFT system analyzes and displays multiple operational deflections shapes at different frequencies after a single excitation from any transient event. Furthermore, the system concurrently computes valuable 3D strain and displacement data that can be displayed alongside the vibration data.
齿轮传动研究 Gear Testing Example
A plastic gear assembly was being evaluated to better understand interactions between component parts. In addition to strain measurements, it was desirable to obtain deflection data in three dimensions
装配在一起的齿轮工作时通常具有复杂的交互作用。 由于齿轮的转动，轮齿接触点在运行周期中会不断变化。 这意味着峰值应变的位置很难预测，而且它们通常不是定值。 零件的转动也导致与传统电测应变片保持连接变得不切实际。 即使工件处于静止且易于定位时，应变峰值也可能集中在非常小的区域或具有高应变梯度变化，而应变片产生的平均效应可能会造成峰值结果的损失。
Assembled components typically have complex interactions with one another. Contact points can vary during operational cycles due to part movement. This means that the locations of peak strains can be hard to predict, and they are often not stationary. The movement of parts can also make it impractical to maintain electrical connections with gauges. Even when they are stationary and easy to locate, the highest strains can be concentrated in very small areas or have high gradients. Peak values may be lost to the averaging effect produced by gauges.
CSI公司的VIC-3D提供了一种可用于齿轮整个轮廓上进行应变测量的方法。 因为它提供了全场测量，所以没有必要选择特定的点进行测量， 这样可以在运行周期的各个阶段清楚地显示和精确测量峰值应变。 VIC-3D同时提供了三维位移的测量数据。 该功能使我们的客户能够识别和量化负载下轮齿的扭转变形。
Correlated Solutions’ VIC-3D provided a means for making strain measurements across the entire profile of the gear tooth. Because it provides full-field measurements, it was not necessary to choose a particular point at which measurements would be made. This allowed the peak strains to be clearly visualized and accurately measured at various stages of the operational cycle. VIC-3D also measured displacement in three dimensions. This feature allowed our customer to recognize and quantify twisting of the gear tooth under load.
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