| With the development of modern industrial technology,the degree of automation for all kinds of mechanical equipment is getting higher.In working process of equipment with largescale and heavy-load,real-time accurate feedback of workload is an important part of ensuring the safe operation of equipment and the coordinated control of its complex working conditions.In order to match the large volume,heavy load,and wide working area of large equipment,various force testing devices also need to have larger installation and adapter sizes.Before used in actual testing,the dynamometer must be calibrated to determine its static performance indicators to obtain high test accuracy.However,the overall rigidity of the test device is reduced under large dimensions.It is prone to large deformation when subjected to external forces,and its test performance can also be seriously affected.In order to overcome the influence of large size and large span and improve the accuracy of vector force testing,this paper takes the large-size multi-point layout piezoelectric dynamometer as research object,and conducts research on the structural size design of dynamometer,the optimization of weak stiffness problems,the calibration of static performance,and the improvement of layout methods.Complete the preliminary design of four-point layout piezoelectric dynamometer.Aiming at the test requirements of test for vector force with variable loading points or simultaneous loading of multiple force sources in a large area,the design requirements of large-size multipoint layout piezoelectric dynamometer are proposed.The finite element analysis method is used to explore the influence law of the span for force measurement unit on output properties of the dynamometer,and the critical span value to change the stable output state is determined.Aiming at the problem of weak rigidity of upper slab under large-span layout,the parameterized design method is used to optimize the key size parameters for the stiffener structure,and the four-point layout rectangular dynamometer is structured.Verify the mechanical output performance of four-point layout dynamometer after the structure is finalized.Set up a piezoelectric test system to statically calibrate the four piezoelectric three-dimensional force measuring units that make up the dynamometer.Perform multi-point step loading experiments on the four-point layout piezoelectric dynamometer to obtain its static performance indicators.Based on the principle of torque balance,the coordinates of variable loading points are calculated to verify the accuracy of dynamometer’s solution to the position of vector force in large area.Aiming at the problem that the lateral interference output is too large when the dynamometer is loaded in main direction,the slender rod displacement model and deformation trend model of dynamometer are established for traceability analysis,and an eight-point layout improvement plan is proposed accordingly.Conduct the research on output performance of the improved large-size dynamometer.The feasibility of eight-point layout scheme was tested by finite element statics simulation.Two eight-point rectangular dynamometers with different layout spans were assembled respectively,and step loading experiment with variable loading points was carried out.The static performance index of the dynamometer and the accuracy of acting position for vector force are analyzed,and compared with the experimental results of four-point layout dynamometer,which proved that the improved scheme greatly improves the test accuracy of dynamometer.Finally,aiming at the problem that the lateral interference output is still large when the inner force measuring unit is arranged with a span of 500 mm,the optimal arrangement span of the force measuring unit is explored by combining the finite element parameterized design method.In this paper,for the needs of large-scale multi-dimensional force testing,the test performance of large-span multi-point layout piezoelectric dynamometer is studied,which provides a certain reference for the related research of force measurement for large-scale industrial equipment. |
