Research On Experimental Technique Of High-speed Dry Friction And The Wear Property

With the development and upgrading of special weapon in modern warfare, rocketsled testing realized a high speed development by satisfying complicate experimentenvironment for running in high speed, carrying heavy load, and providing safe andstable platform. In rocket sled system, the surface contact problem between slider andthe rail is one of the key problems, which is a typical high speed dry sliding frictionproblem. To achieve effective analysis, a high speed dry sliding testing equipment wasmade in this project, and a unique data analysis method was introduced. All of theseprovide a validation reference for research on rocket sled testing system.In this paper, an experimental equipment was proposed to measure the coefficientof dynamics friction under high speed and high impact load, Which is based on theclassic tribology theory. The equipment consists four parts, the one-stage light gas gunprovided the power to push the bullet impacting a testing object in high speed; the lasermeasuring system monitors the bullet’s impact velocity and the friction pair’s finalvelocity; the force ring real-time monitors the press on friction pair; and the measuringunit measures the friction generated by the friction pair’s relative movement. Before atest, the force ring and the measuring unit were well validated. This equipment canachieve a velocity load ranges from10m/s to100m/s, and a press load which is lowerthan10kN.A series of experiment for a structural steel, under different velocity, differentpress, different roughness, was implemented in the equipment. Besides, an electronmicroscopy was utilized to observe the surface of friction pair, and to measure thesurface roughness. By applying the numerical analysis method, the arithmetical meandeviation of the profile Ra, a quantification factor for surface roughness, can beobtained. By observing the measuring result, a numerical analysis method wasproposed with a three dimensional (vij, Fij, ij) model. Besides, a supplementaryexperiment was implemented by finite element analysis. By analyzing the experimentresult, a series of conclusions were discovered. Firstly, the normal press and surfaceroughness have negative correlation to friction coefficient. Secondly, the relationshipbetween velocity and friction would be influenced by normal press, when the normalpress is less than3.2kN, the velocity have positive correlation with friction coefficient, otherwise when the normal press is larger than3.3kN, the velocity have negativecorrelation with the friction coefficient. Lastly, the normal press has positivecorrelation with surface roughness deceasing percent, but the sliding velocity have theopposite trend.