實驗研究
(中南大學(xué) 粉末冶金國家重點實驗室，長沙 410083)
摘 要: 為了探明汽車盤式摩擦片剪切強度不穩(wěn)定的原因，用數(shù)值方法模擬摩擦片熱壓成形過程中溫度分布和模具局部失效對粉末流動和固結(jié)的影響， 并進行了相應(yīng)的實驗分析和驗證。 結(jié)果表明： 模具局部失效及溫度梯度分布造成基體材料溢出，基體材料的流動導(dǎo)致在剪切面上纖維集合定向排列， 從而大幅度降低試樣的剪切強度； 當(dāng)基體出現(xiàn)剪切層， 導(dǎo)致纖維成定向分布時， 剪切強度明顯下降， 低于要求的0.4 MPa(最高值僅為0.356 MPa)， 而在無溢出情況下， 剪切強度都高于0.4 MPa。
關(guān)鍵字: 盤式摩擦片；粉末冶金； 熱壓成形； 數(shù)值模擬
（ State Key Laboratory of Powder Metallurgy,
Central South University, Changsha 410083, China）
Abstract: To find out the causes about unstable shear strength of PM disk break pad, the hot press process of PM disk brake pad was numerically simulated by using finite element method. The influence of temperature distribution and mould failure on powder flow and consolidation was analyzed, and the corresponding experiments were conducted. The effect of powder flow on fiber orientation and shear strength was unveiled. The results show that mould failure and temperature gradient can lead to obvious flow of matrix in the shear direction. The flowing of matrix can result in oriented arrangement of fiber in shear direction and greatly reduce the shear strength of samples. In the situation of fiber orientation caused by shear layer, the pads' shear strength can only reach 0.356 MPa; while in normal condition it can attain to 0.4 MPa or higher.
Key words: disk brake pad; powder metallurgy; hot press; numerical simulation
