| Vibration caused by friction will lead to system instability and thus reduce the accuracy,stability and service life of mechanical equipment,and the resulting noise will seriously pollute the ecological environment,endangering people's physical and mental health.Therefore,vibration and noise reduction has become an urgent problem to be solved today.In recent years,it has become a quick and effective way to reduce or prevent vibration and noise by the use of damping alloys with high damping performance made of vibration and noise sources and other mechanical structure parts.However,it is more common that two objects which are in contact with each other due to unavoidable external factors occurs relative sliding friction and generate vibration and noise in the actual production life.Therefore,it is very innovative and practicable to study the influence of damping alloy on sliding friction vibration noise when it is directly used as the friction between the grinding material,which can provide some guidance for controlling the problem of friction-induced vibration and noise.In this paper,in order to study the sliding friction-induced vibration and noise characteristics of the new Mn-Cu damping alloy with high damping performance,firstly we choose the four kinds of traditional metal alloys,such as vermicular graphite cast iron(RuT350),forged steel(20CrMnMo),ductile iron(QT400)and aluminum alloy(7075)with low vibration damping performance as the comparative materials to carry out the ball-disc sliding friction-induced vibration and noise tests under the ball-plane contact mode.Then we select vermicular cast iron and forged steel two kinds of metal alloys as the comparative materials to carry out the pin-disc sliding friction-induced vibration and noise tests under the plane-plane contact mode.Through the analysis of the friction noise sound pressure,vibration acceleration and dynamic friction and other signal which were measured in the friction test and the surface wear morphology after the test,we mainly studies the effects of three materials such as Mn-Cu damping alloy on the friction noise characteristics,the interface vibration characteristics and wears behavior.In addition,the influence and difference of friction and noise between Mn-Cu damping alloy and other materials in the two modes are compared and analyzed.And it will try to explain the reasons and influence mechanism for the existence of differences of damping alloy through combing with the wear surface morphology of the specimen.The main conclusions are as follows:1?In the ball-disc friction noise test,vermicular cast iron,forged steel and ductile iron material are easy to produce high-intensity,multi-frequency friction squeal noise when the test continues for a certain period of time,while the aluminum alloy material in the initial stage of the test appeared a higher sound pressure level of the continuous friction noise and continued to the end of the test.In the experimental stabilization phase the vibration acceleration and friction noise sound pressure time domain signal of the four materials'friction system appears significant continuous wave and vibration amplitude is larger;In contrast,Mn-Cu damping alloy in the whole process can only form a low sound pressure level,low frequency friction noise,the vibration and sound pressure time domain signals of the friction system do not show significant continuous large amplitude fluctuation.2?In the pin-disc friction noise test,the effects of vermicular cast iron,forged steel and damping alloy material on the friction noise and vibration characteristics have the same rules and trends under two normal loads:three materials in the test all have produced a high sound pressure level and more complex frequency components friction screaming noise,and the noise intensity from low to high order followed by vermicular cast iron,damping alloy and forged steel,the latter two vibration acceleration and sound pressure time domain signal waveform is more continuous and more volatile volatility than the vermicular cast iron.3?There are obvious differences in the interface friction and wear behavior of the different materials under the same contact mode.Under the ball-plane contact mode,the width of vermicular cast iron,forged steel and ductile iron material which have been grinded is small.In the surface of wear area,abrasive dust accumulation,furrows and spalling are extremely obvious.The surface of polishing scratch exist obvious uneven outline.In contrast,the grinding crack width of Mn-Cu damping alloy and aluminum alloy material is greater and quite deep.A bunch of abrasive dust has been manufactured and concentrated in the grinding marks on both sides,grinding crack area is given priority to smooth ploughing characteristics,and the contours of the surface wear are relatively flat.In the plane-plane contact mode,the worn surface of vermicular cast iron,forged steel and damping alloy material appears different degree of wear debris accumulation of "third body" layer,furrows and adhesive peeling phenomena.The grinding behavior of vermicular cast iron is mainly based on the furrow phenomenon and the wear characteristics are relatively slight.The wear characteristics of Mn-Cu damping alloy and forged steel are more prominent,and the surface morphology is more "complicated".4?under the operating conditions of this test,the mechanism of Mn-Cu damping alloy material affects the friction-induced vibration and noise mainly includes two parts:the damping mechanism of the material itself and the interface "irregularities" characteristics resulted from the wear debris accumulation of "third body" layer,furrows and adhesive peeling on worn surface caused by the interface effect.In the ball-plane contact mode,due to the combination of the damping mechanism and furrow wear characteristics caused by the slight interfacial effects,Mn-Cu damping alloy material's friction system does not appear violent unstable self-excited vibration,and correspondingly yields only low intensity,low frequency friction noise.However under the plane-plane contact mode,due to the severe accumulation of wear debris and detachment on grinding crack area caused by the strong interfacial effects plays a major role,while the effect of the damping mechanism of the material itself is relatively weaker,so the friction system strongly occurs unstable self-excited vibration,and correspondingly generates high sound pressure level,the frequency component of the more complex friction squeal noise. |
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