Search results for "test method"
showing 7 items of 17 documents
Validation of frictional studies by double-cup extrusion tests in cold-forming
1996
Abstract Studies on frictional conditions in cold-forming have shown that, for a given lubricant, friction factor values are strongly affected by the test method. In the present paper, different cold-forging processes of an aluminium alloy, are modelled by a FEM numerical code using the m values obtained by both the double cup extrusion and ring compression tests. It appears that the m values given by the ring tests can be effectively used in the simulation of upsetting processes, while the m values derived by the double cup extrusion tests are more appropriate for predictions in extrusion and closed-die forging operations.
Robustness of Empirical Vibration Correlation Techniques for Predicting the Instability of Unstiffened Cylindrical Composite Shells in Axial Compress…
2020
Thin-walled carbon fiber reinforced plastic (CFRP) shells are increasingly used in aerospace industry. Such shells are prone to the loss of stability under compressive loads. Furthermore, the instability onset of monocoque shells exhibits a pronounced imperfection sensitivity. The vibration correlation technique (VCT) is being developed as a nondestructive test method for evaluation of the buckling load of the shells. In this study, accuracy and robustness of an existing and a modified VCT method are evaluated. With this aim, more than 20 thin-walled unstiffened CFRP shells have been produced and tested. The results obtained suggest that the vibration response under loads exceeding 0.25 of …
Bond strength of metal-ceramic systems in three-point flexure bond test
1995
This study deals with a three-point flexure test for the metal-ceramic bond involving geometrically simple specimens (alloy strips partly coated with ceramic) that can be fabricated with reasonable expenditure and sufficient reproducibility. The calculation of the stress distribution in such specimens with the aid of the finite-element method (FEM) is presented. The aim of this numerical analysis is: to investigate the stress distribution in a ceramometallic specimen with dimensions that, in a large number of experiments, have proven to lead to debonding at one end of the ceramic veneer instead of a crack in the middle of the veneer; and to assign a bond strength to the measured critical be…
Radiation Hardness Assurance Through System-Level Testing: Risk Acceptance, Facility Requirements, Test Methodology, and Data Exploitation
2021
International audience; Functional verification schemes at a level different from component-level testing are emerging as a cost-effective tool for those space systems for which the risk associated with a lower level of assurance can be accepted. Despite the promising potential, system-level radiation testing can be applied to the functional verification of systems under restricted intrinsic boundaries. Most of them are related to the use of hadrons as opposed to heavy ions. Hadrons are preferred for the irradiation of any bulky system, in general, because of their deeper penetration capabilities. General guidelines about the test preparation and procedure for a high-level radiation test ar…
Performance Measurement of Mobile Manipulators
2015
International audience; This paper describes a concept for measuring the reproducible performance of mobile manipulators to be used for assembly or other similar tasks. An automatic guided vehicle with an onboard robot arm was programmed to repeatedly move to and stop at a novel, reconfigurable mobile manipulator artifact (RMMA), sense the RMMA, and detect targets on the RMMA. The manipulator moved a laser retroreflective sensor to detect small reflectors that can be reconfigured to measure various manipulator positions and orientations (poses). This paper describes calibration of a multi-camera,motion capture system using a 6 degree-of-freedom metrology bar and then using the camera system…
Navigation Performance Evaluation for AutomaticGuided Vehicles
2015
International audience; —Automatic guided vehicles (AGVs), an industrial form of a mobile robot,typically navigate using a central computer commanding AGV movement on predefined paths. How well they follow these paths is not well-defined in research articles and their performance is reported in non-standard manufacturer specifications. Furthermore, AGV technology is advancing towards vision guidance to map and localize their position from onboard the vehicle, whereas performance evaluation of advanced navigation techniques is just beginning. This paper describes AGV experiments using ground truth measurement comparisonfor performance evaluationof AGV navigation. A generic test procedure and…
Survey of Research for Performance Measurement of Mobile Manipulators
2016
International audience; This survey provides the basis for developing research in the area of mobile manipulator performance measurement, an area that has relatively few research articles when compared to other mobile manipulator research areas. The survey provides a literature review of mobile manipulator research with examples of experimental applications. The survey also provides an extensive list of planning and control references as this has been the major research focus for mobile manipulators which factors into performance measurement of the system. The survey then reviews performance metrics considered for mobile robots, robot arms, and mobile manipulators and the systems that measu…