Development Of Reciprocating Dynamic Load Friction And Wear Testing Machine And Study Of Typical Material Wear Behavior Under Dynamic Load

Carrier equipment is usually in service under dynamic loads,and its gearboxes,internal combustion engines and other key components frictional subsets exhibit a variety of complex frictional wear behaviors.However,most of the existing tribological studies have been conducted under constant load,and the test results are still difficult to explain some of the wear phenomena in engineering.Preliminary results of dynamic load tests show that some materials exhibit significantly different results from constant load tests under dynamic load.At the same time,there is a lack of commercial dynamic load friction and wear testing machines,which also restricts the study of the effect of dynamic load on friction and wear laws.In this thesis,the law and mechanism of the effect of dynamic load on frictional wear behavior is investigated for two typical types of frictional sub-materials（alloy cast iron used for preparing cylinder liners,and aluminum bronze and tin bronze commonly used for preparing frictional sub-materials under dry friction conditions）using an electromagnetically excited dynamic load reciprocating frictional wear testing machine.The main conclusions obtained are as follows.（1）The developed reciprocating dynamic load friction and wear tester couples the electromagnet with the original reciprocating sliding friction and wear tester loading mechanism to realize a normal dynamic load loading method with adjustable dynamic force amplitude and frequency.The tester can apply a constant maximum load of 300 N,a dynamic load range of 5%～15%of the constant load,and a dynamic load frequency of 40 Hz～90 Hz.（2）The effect of dynamic load characteristics on the tribological properties of cast iron was investigated by designing orthogonal tests according to the orthogonal table of L₉（3⁴）by varying the dynamic force,dynamic frequency,constant load and temperature,and it was found that the wear of cast iron under dynamic load was higher than that under constant load.（3）The wear of cast iron increases with the increase of dynamic load frequency and dynamic force,and the friction force under dynamic load is lower than that under constant load,and decreases with the increase of dynamic load frequency and dynamic load force.（4）The wear of aluminum bronze and tin bronze increases with the increase of dynamic load frequency and dynamic force,and the friction force of tin bronze under dynamic load decreases with the increase of dynamic frequency and dynamic force.The friction force of aluminum bronze does not change significantly with dynamic frequency in the interval of40～80Hz,and decreases with the increase of dynamic force.（5）The wear amount of different materials for dynamic load"sensitivity"is different.Dynamic load frequency in the range of 40～60 Hz,aluminum bronze in the dynamic load and constant load wear difference of less than 30%,more suitable for application in the dynamic load under the friction conditions.At 5%of dynamic force,the wear increase of tin bronze under dynamic load is the largest among the three test materials,which means that tin bronze is not suitable for low dynamic load friction conditions.When the dynamic force ratio is increased to 10%-15%,the wear increase of aluminum bronze is the lowest among the three test materials.In summary,aluminum bronze has better adaptability to dynamic loads in the40～60Hz dynamic load range.