Tham khảo tài liệu 'friction and lubrication in mechanical design episode 2 part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 380 Chapter 9 remain near normal. The configuration of the joint is shown on Fig. . A schematic diagram is given in Fig. to show the animal s leg in place with the static load and cyclic rubbing motion identified. A special fixture is designed for applying constant compressive loads to the joint Fig. . It has a spring-actuated clamp which can be adjusted to apply static Figure Schematic representation of applied load and rubbing motion. Case Illustrations of Surface Damage 381 Figure Constraining rig showing the fixture for application of compressive load. loads between 450 g and kg. The spring is calibrated for continuous monitoring of the normal load which is applied to the rat joint through a soft rubber pad. Test Specimens The test specimens were all male white albino rats. Their weight varies from 300 to 350 g. The rats were maintained on mouse breeder blox and water. The room temperature was kept between 80 and 84 F. Nine rats were tested in this study with each three specimens subjected to identical load levels. Test Plan The right tibia of each rat was subjected to an alternating pull force between and 90 g at a rate of 1500 cycles min. All the tests were conducted at this value of the cyclic load with the compressive normal load fixed at and kg respectively. The duration of the testing was 2-3 hr every day for a period of 14 days. After that period the rats were sacrificed and the 382 Chapter 9 different tests were performed on the joint. Only the temperature data were obtained while the rats were tested. Temperature Measurements The temperature over the skin of the rat at the patella joint is measured by thermocouples. The combination used is iron and constantan and the temperature can be continuously recorded with an accuracy of F. A typical variation of temperature on both the loaded and unloaded joints is shown in Fig. . The compressive load on the test joint is kg in this case. The .
