A thrust stand is developed for measuring the pulsed thrust generated by low-thrust liquid pulsed rocket engines. It mainly consists of a thrust dynamometer, a base frame, a connecting frame, and a data acquisition and processing system. The thrust dynamometer assembled with shear mode piezoelectric quartz sensors is developed as the core component of the thrust stand. It adopts integral shell structure. The sensors are inserted into unique double-elastic-half-ring grooves with an interference fit. The thrust is transferred to the sensors by means of static friction forces of fitting surfaces. The sensors could produce an amount of charges which are proportional to the thrust to be measured. The thrust stand is calibrated both statically and dynamically. The in situ static calibration is performed using a standard force sensor. The dynamic calibration is carried out using pendulum-typed steel ball impact technique. Typical thrust pulse is simulated by a trapezoidal impulse force. The results show that the thrust stand has a sensitivity of 25.832 mV/N, a linearity error of 0.24% FSO, and a repeatability error of 0.23% FSO. The first natural frequency of the thrust stand is 1245 Hz. The thrust stand can accurately measure thrust waveform of each firing, which is used for fine control of on-orbit vehicles in the thrust range of 5-20 N with pulse frequency of 50 Hz.
The purpose of this paper is to show the investigation on a type of unitary piezoelectric four-component cutting dynamometer. Based on piezoelectric effect of quartz crystal, such as torsion effect, transverse effect, lengthways effect and shearing effect, horizontal moment and three-direction orthogonal forces carried on the dynamometer during cutting process can be measured simultaneously. The dynamometer can be used to measure forces and horizontal moments in drilling, grinding, milling, turning. A secondary purpose is to optimize structure parameters of the dynamometer by ANSYS. The dynamometer has good performance with high sensitivity, good linearity and repeatability and low crosstalk after optimizing.
A method is presented for determining the pouring point location of concrete pump truck. The method does not change the structure of the concrete pump truck, only need to replace the hydraulic cylinders of booms with the hydraulic cylinders with displacement senor, and the displacement sensors are mounted in the inside of the hydraulic cylinders and do not need any extra protection. The relationship formulas between the contraction and expansion amounts of the hydraulic cylinders and the pouring point location are derived and programmed to input into a data processing unit. The contraction and expansion amounts of the hydraulic cylinders are timely acquired and inputted into the data processing unit, then the pouring point location can be displayed in real-time on the screen of radio controller, and the workers can quickly and accurately locate the pouring point of the concrete pump truck to poured point.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.