Application Example: Automotive Testing: Optical 3D Metrology improves Safety and Comfort Measuring System: PONTOS, ARAMIS, TRITOP, ATOS, GOM Touch Probe Keywords: Automotive, Crash Testing, static and dynamic Deformation, Simulation Verification, optical 3D Metrology, 6DoF Analyses Product development in the automotive sector is currently driven by strong competition, which causes shorter development cycles and high cost pressure. At the same time, the automotive industry has to respond to the stricter regulations aiming to reduce environmental emissions. As a result, automobile manufacturers need to implement lightweight construction materials and new material combinations to reduce vehicle weight and, in consequence, lower fuel consumption. Nevertheless, the new materials must also meet the high standards of performance, safety and durability. GOM mbh Mittelweg 7-8 38106 Braunschweig Germany Phone +49 531 390 29 0 Fax +49 531 390 29 15 info@gom.com GOM International AG Bremgarterstrasse 89B 8967 Widen Switzerland Phone +41 5 66 31 04 04 Fax +41 5 66 31 04 07 international@gom.com GOM UK Ltd Unit 14, The Cobalt Centre Coventry, CV3 4PE United Kingdom Phone +44 2476 639920 Fax +44 2476 516990 info-uk@gom.com GOM Asia Keyuan Road 88, Tower 2, Unit 731 201203 Shanghai PR China Phone +86 21 2898 6551 Fax +86 21 2898 6552 info-asia@gom.com GOM France SAS 10 Quai de la Borde 91130 Ris Orangis France Phone +33 1 60 47 90 50 Fax +33 1 69 06 63 60 info-france@gom.com GOM Branch Benelux Interleuvenlaan 15 F 3001 Leuven Belgium Phone +32 16 408 034 Fax +32 16 408 734 info-benelux@gom.com GOM Italia Srl Via della Resistenza 121/A 20090 Buccinasco (MI) Italy Phone +39 02 457 01 564 Fax +39 02 457 12 801 info-italia@gom.com www.gom.com Copyright 2014 GOM mbh All rights reserved! Rev. A (en) 171014 1
Application Example: Automotive Testing: Optical 3D Metrology improves Safety and Comfort Measuring System: PONTOS, ARAMIS, TRITOP, ATOS, GOM Touch Probe Keywords: Automotive, Crash Testing, static and dynamic Deformation, Simulation Verification, optical 3D Metrology, 6DoF Analyses Optical Measurements replace conventional Systems in Crash and Fatigue Testing To speed up design, simulation and development cycles, the automotive industry now increasingly uses optical measurement systems, instead of conventional strain gauges, accelerometers, transducers and extensometers. Companies implement these non-contact systems not only in crash and impact tests, but also in climate chamber, wind tunnel and fatigue testing. Particularly important for car manufacturers such as Audi, BMW, Daimler, Porsche and Volkswagen, as well as suppliers such as Autoliv, Bosch, Continental, TRW and ZF, is the fact that the optical measuring systems can be fully and effortlessly integrated into existing test facilities and test stands. Non-contact Measurement of Displacement, Speed and Acceleration Optical sensors provide data of part and component geometries, as well as of three-dimensional displacements and deformations. Static and dynamic deformations are determined on the basis of individual points as well as entire surfaces. With this data, manufacturers can evaluate part safety and functioning, while also optimizing their simulation and design processes at the same time. As a result, product development can be noticeably accelerated. The most interesting aspect for test engineers is how parts and components react during crash and impact tests this is the only way to guarantee the safety of passengers and pedestrians. (Fig. 1) Fig. 1: Point-based systems like PONTOS show 3D displacement vectors and a full 6DoF analysis of the dummy s head movements. Trajectories can also be evaluated and visualized. Copyright 2014 GOM mbh All rights reserved! Rev. A (en) 171014 2
Therefore a precise analysis of the dynamic behavior of individual parts and components is necessary. For better visualization and understanding, the systems provide point-based as well as full-field measurement data. Optical measuring systems are applied not only in crash and impact, but also in wind tunnel tests, chassis and engine test stands, in vibration analysis, as well as in door and closure testing. 6DoF Analyses in Crash Testing Sled testing, for example, typically uses point-based measurement processes as a fast method for testing seats, body restraint systems and interior trim components. These test setups do not involve the destruction of costly prototypes or entire vehicles, as they are simply accelerated to predefined speeds. This makes it possible to demonstrate the impact of frontal, side and rear crashes at low cost. Point-based systems like PONTOS show 3D displacement vectors, while additionally measuring real speed and acceleration in any test setup. The collected measurement data is used, for example, to determine the movement of seats and crash test dummies. The evaluation enables full 6DoF analysis of movements, including the rotation and translation motions e. g. of a dummy s head. Additionally, body movements and rotation, including trajectories, are measured, as well as the speed at which the head hits the headrest, and leg movements. During this process, displacements of the measured points are displayed in 3D. Test engineers use the data to analyze precisely how the dummy s head and body will move within a given space. This, in turn, makes it possible to draw conclusions about the safety of seat and belt systems, but also shows whether there is a risk of head impact inside the vehicle. (Fig. 2) Fig. 2: Based on the measurement data, test engineers can analyze precisely how the dummy s head and body will move inside the car. This in turn makes it possible to draw conclusions about the safety of seat and belt systems, but also shows whether there is a risk of head impact inside the vehicle. Copyright 2014 GOM mbh All rights reserved! Rev. A (en) 171014 3
Point-based measurement systems are easy to integrate in various test stands. Inspection points are identified via measurement markers. In addition, test setup is accelerated due to an integrated positioning function: an optically tracked touch probe quickly determines and marks the positions specified by testing regulations, e. g. for dummies and seats. The measurements are easily performed even in rough environments, because of the integrated strong illumination and a flexible image recording trigger. Image recording rates of up to 1,000,000 Hz are achieved for setups ranging from long-term tests to high-speed applications. Furthermore, analog channels (force, distance, angle, temperature, etc.) can be recorded simultaneously. Making full-field Strain and Displacements visible For other testing setups full-field information relating to dynamic deformations is vital for components that are of relevance to safety. As a consequence, fullfield measurement systems (e. g. ARAMIS) are frequently used in crash and impact tests, as well as in component testing, for instance on airbags and on tire test rigs. Airbag housing and airbag inflation characteristics are analyzed with high-speed cameras. The full-field measurement data is then used to calculate surface strain and planar displacements for all axes. Crash tests are another area in which fullfield measurement systems are deployed, for components such as windshields. Since modern car windows consist of several material layers, numerical simulations are often inaccurate for determining their behavior under load. The fullfield measurement data recorded by the high-speed cameras of the ARAMIS system can then be used to draw reliable conclusions on crack propagation in a windshield that otherwise stays invisible. (Fig. 3) Fig. 3: The full-field measurement data recorded by the high-speed cameras of the ARAMIS system can be used to draw reliable conclusions on crack propagation in a windshield. Copyright 2014 GOM mbh All rights reserved! Rev. A (en) 171014 4
Environmental Testing: Analysis of static Deformations Quality assurance covers not only dynamic part and component behavior, but also static deformations in a before/after comparison. Portable optical systems such as TRITOP determine the coordinates of three-dimensional objects by means of photogrammetry. Systems of this type are used in climate chamber tests to analyze point-based deformations and changes in gap and flush dimensions under various temperature and environmental conditions. Measurements enable conclusions to be drawn on material stiffness as well as on design quality. Photogrammetry systems are also used to document the state of a vehicle before and after a frontal crash test. On the basis of the 3D coordinates from the two measurement stages, point deformation vectors on the x-, y- and z-axes can be determined, making it possible to understand deformations at the A, B and C pillars, for example. Where point-based measurement is inadequate, optical 3D scanners such as ATOS are available to acquire a full-field description of the part geometry and to make static deformations visible. These 3D scanners collect full-field data on complete chassis, individual parts and components, as well as on barriers before and after testing. Scanning data of barriers for example displays a complete impression of the test automobile, making it easier to assess energy absorption during a frontal crash. Optical Metrology increases Comfort, Durability and Safety In the automotive sector tighter safety regulations and varying international standards make it necessary to have a metrology system that is flexible and easy to adapt. Today s optical measuring systems perform static, dynamic, point-based and full-field analyses in a non-contact way. Measurement areas, frame rates and resolution can be adjusted to the different test setups. This replaces conventional strain gauges, accelerometers, transducers and extensometers. The recorded 3D measurement data is permanently available and can be evaluated after testing and in different contexts. The measurement results can be displayed in diagrams, videos and images. (Fig. 4) Fig. 4: Evaluation video with diagram of a side impact crash test to measure the intrusion of B-pillar and door into the passenger compartment. Copyright 2014 GOM mbh All rights reserved! Rev. A (en) 171014 5
The 3D measurement data is used to draw conclusions on safety risks, part durability, creep and aging processes, and on changes to outer appearance during part lifetime and usage. This results in improved safety and comfort as well as longer durability and more attractive product design. Simulation Verification The measurements are also used in simulation verification to review and improve simulation parameters, as well as to optimize current and future design processes. As a result, users can reduce the overall number of test runs and consequently speed up product development. This means a competitive advantage for manufacturers and suppliers in a market that is subject to high cost and innovation pressure. Copyright 2014 GOM mbh All rights reserved! Rev. A (en) 171014 6