| Summary: | 碩士 === 淡江大學 === 土木工程學系 === 90 === Shear stress relates closely to actual wear areas of joints. Article studies residual wear areas by two synthetic joint surfaces and proceeds experiment by blue surface samplings and making black samplings. After shearing , we can obtain wear and attachment region, and then take a CCD picture to know wear area by photo image technology and pixel analysis. Article utilizes wear area to investigate connected mechanics behavior.
The main conclusions are drawn as follows. (1) Shear stress, wear area , and cohesion tend to be a stabile value at residual state. The shape, size, and spatial distribution of wear areas primarily depended upon the shearing direction, the initial roughness degree, and the stress level. At moderate stress levels(σn /JCS=1/140∼1/28), the ratio of wear areas ranges from 1.8 to 6.5% at peak state；the ratio of wear areas ranges from 2.6 to 13% at residual state.(2) Article selects an angle equal to the residual dilation angle, and draws contour map at this angle to obtain the shape and spatial distribution of wear areas at residual state. (3) During shearing, the ratio of wear areas can show the local stress multiple , and the local stress multiple is the inverse to the ratio of wear areas.(4) Article proposes a formula of wear areas byσn /JCS and JRCo. The formula is expressed as follow：
as=-3+0.4JRC+363(σn /JCS)
By the formula, we can know that roughness has noticeable influences for wear areas at low stress levels. To take one step ahead, article proposes a formula of residual stress expressed：
τr=σn(ψb+JRC(res)‧log(JCS/σn)
in the formula：JRC(res)=(σn /JCS)**0.2‧(JRCO)**0.8. If φb、 σn have known, this formula can use as formula of wear areas to predict residual stress by as, JRCo,or JCS.
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