New tools will predict and correlate data for materials and structural engineers.
Adding Digital Image Correlation to the Toolbox
Simcenter Testlab is a group of modeling, testing and analytical tools used at test labs and manufacturing centers. The software has a wide array of applications, including acoustical testing, structural testing and dynamic environmental tests. As product and process development continue their slow shift from physical prototypes to a more virtual test environment, Siemens is working to make the additional simulation studies more valuable to their customers. The recent 2021.1 release of Testlab added Digital Image Correlation (DIC) for materials and structural testing.
The DIC technology uses two digital cameras to scan thousands of points on an object’s surface. The images give a 3D geometry of a part as well as 3D displacement as the part is put through a test. Through these two sets of data, the digital image correlation can build a model with the spatial resolution of a finite element model.
Materials Testing Gets a Digital Image Boost
Using DIC in materials testing has a few advantages over traditional methods. Materials engineers are trying to find the right combination of cost savings and weight savings while keeping structural properties up to code and not causing any new noises in vehicles. DIC can measure sound absorption and sound transmission losses in a system by calculating a material’s properties and displacements.
The virtual fields method can be used to find properties of an unknown material. This will help engineers perform reverse engineering on competitors’ products or find possible replacement materials when redesigning a system. This materials property data can also be used by engineering team members when performing simulations on new parts.
Structural Engineers Benefit from Measuring 3D Data Everywhere at Once
Studying a part under load used to require building a prototype of the physical part and then placing the part in a test fixture. The development of finite element analysis (FEA) provided the ability to run virtual tests on a computer to predict the behavior of the component and any possible weak points in the system. Digital image correlation can help engineers in a zone between physical prototyping and virtual tests by creating data from the components. The sample is painted with dots and the cameras follow the movements of those dots during the test.
The software takes those dots and builds a full-field displacement model of the component. The displacement model can predict strain, displacement and acceleration data of the part or system. This data can also be correlated to FEA to verify the accuracy and reliability of the virtual results.
Ground vibration testing (GVT) helps aerospace engineers collect vibration data from a full aircraft structure to validate its structural dynamic models. On many product schedules, GVT is performed at the end of the development cycle, and engineers are crunched for time to produce accurate results quickly. DIC has helped to provide flutter predictions and plan safety critical validation tests. Siemens says that using DIC has reduced GVT cycles from weeks to days on recent commercial and military aircraft programs. The Airbus A380 recently used DIC to take data from over 100 sensors, build accurate flutter models, and remove noise from the results.
This new method of taking image and displacement data makes digital image correlation seem like a completely new process. In the last 15 years, digital scanners went from being expensive data collection tools to more common devices. Many makers built their own scanners using 3D printers, old projectors, or video game console capture cameras. But adding in the dimension of displacement in real time takes everything to a completely different level. Looking through these pages still yields pictures of white parts with dots, but that’s about the only similarity to a digital scanner.