本文選題：激光直接金屬沉積 + 功能梯度復(fù)合材料�。� 參考：《華東交通大學(xué)》2015年碩士論文

【摘要】：石墨-銅功能梯度復(fù)合材料具有優(yōu)異的導(dǎo)熱、導(dǎo)電和自潤滑性能，在軌道交通、電力傳輸?shù)阮I(lǐng)域具有廣闊的應(yīng)用前景。本文采用ANSYS軟件對激光直接金屬沉積石墨-銅功能梯度復(fù)合材料過程的溫度場和應(yīng)力場進(jìn)行了研究。 借助于APDL語言的二次開發(fā)以及生死單元技術(shù)對多層單道的激光直接金屬沉積過程進(jìn)行了仿真計(jì)算，并且采用間接耦合的方式對溫度場進(jìn)行了熱應(yīng)力耦合，建立了激光沉積均質(zhì)復(fù)合材料和功能梯度復(fù)合材料的應(yīng)力場；獲得了激光功率、掃描速率和掃描方式等工藝參數(shù)與梯度分布指數(shù)、層數(shù)和層厚等結(jié)構(gòu)參數(shù)對石墨銅功能梯度復(fù)合材料開裂的作用機(jī)制，得出以下結(jié)論： （1）均質(zhì)復(fù)合材料的等效殘余應(yīng)力比功能梯度復(fù)合材料大，且大應(yīng)力遍布于整個(gè)材料；梯度復(fù)合材料的等效殘余應(yīng)力由底層到頂層依次變小，即梯度結(jié)構(gòu)對殘余應(yīng)力起到了緩和作用。 （2）激光功率在3600W-4200W范圍內(nèi)，，隨著功率的遞增，殘余應(yīng)力平均值先增大后減小，并且功率4200W時(shí)平均殘余應(yīng)力最小；掃描速率在200mm/min-400mm/min范圍內(nèi)，平行于X軸路徑的X向殘余應(yīng)力平均值先增小后增大，掃描速率為300mm/min時(shí)平均殘余應(yīng)力最小；結(jié)合層與層之間的粘結(jié)強(qiáng)度分析，功率的最佳范圍為4000W-4200W,掃描速率最佳范圍為300mm/min-400mm/min。 （3）往復(fù)式掃描比單向式掃描的各向殘余應(yīng)力更小，且殘余應(yīng)力分布均勻。 （4）梯度分布指數(shù)0.25-4范圍內(nèi)，P=1時(shí)材料殘余應(yīng)力整體較�。辉趯雍�0.4mm-0.8mm以及層數(shù)6-10層范圍內(nèi)，得知隨著層厚的加厚以及層數(shù)的增多，制件沿各個(gè)路徑的殘余應(yīng)力都逐漸遞增；綜合分析得出梯度分布指數(shù)P=1、層厚0.6mm、8層為最優(yōu)結(jié)構(gòu)參數(shù)。 （5）功能梯度復(fù)合材料中平行于X軸路徑的X向殘余應(yīng)力的極大值出現(xiàn)在左側(cè)3mm處或右側(cè)31mm處，這兩處區(qū)域的應(yīng)力值較大,是產(chǎn)生沿Y向裂紋的高發(fā)區(qū)；平行于Y軸路徑的Y向殘余應(yīng)力曲線呈“W”型，即在路徑的中間部位以及兩端的應(yīng)力較大；平行于Z軸路徑的Z向殘余應(yīng)力由沉積件底部至頂部逐漸減小，即基板與沉積件之間容易開裂。
[Abstract]:Graphite-copper functionally gradient composites have excellent thermal conductivity, electrical conductivity and self-lubricating properties, and have a broad application prospect in rail transit, electric power transmission and other fields. In this paper, the temperature field and stress field of graphite-copper functionally gradient composites deposited by laser direct metal are studied by ANSYS software. With the help of the secondary development of APDL language and the birth and death element technique, the laser direct metal deposition process with multi-layer and single channel is simulated, and the thermal stress coupling of temperature field is carried out by indirect coupling method. The stress field of homogeneous composites and functionally graded composites deposited by laser was established, and the laser power, scanning rate and scanning mode were obtained, and the gradient distribution index was obtained. The mechanism of crack cracking of graphite-copper functionally gradient composites with structural parameters such as number of layers and thickness of layers is discussed. The conclusions are as follows: (1) the equivalent residual stress of homogeneous composites is larger than that of functionally graded composites. The equivalent residual stress of gradient composites decreases from the bottom layer to the top layer, that is, the gradient structure plays a moderating role on the residual stress, and the laser power increases with the increase of the power in the range of 3600W-4200W. The average value of residual stress increased first and then decreased, and the average residual stress at power of 4200W was the smallest, and the scanning rate was in the range of 200mm/min-400mm/min, and the average value of X-ray residual stress parallel to the X axis path increased first and then increased. When the scanning rate is 300mm/min, the average residual stress is the smallest, and the optimum power range is 4000W-4200W for bond strength analysis between layers, and the optimal scanning rate is 300mm / min-400mm / min.n.) the reciprocating scanning is smaller than the unidirectional scanning. And the residual stress distribution is uniform. The gradient distribution index is 0.25-4. The residual stress of the material is smaller in the range of 0.25-4, and in the range of 0.4mm-0.8mm and 6-10 layers, it is found that with the thickening of the layer thickness and the increase of the number of layers, the residual stress of the material is relatively small in the range of 0.25-4. The residual stress along each path increases gradually. Comprehensive analysis shows that the gradient distribution index Pu 1 and the layer thickness 0.6 mm / L are the optimal structural parameters. The maximum value of the X direction residual stress parallel to the X axis path in the functional gradient composite appears at the left 3mm or the right side 31mm in the functional gradient composite, and the maximum value of the X direction residual stress in the functional gradient composite is found at the left side or the right side of the composite. The stress values of these two regions are larger, and the Y direction residual stress curves parallel to Y axis path are "W" type, that is, the stresses in the middle part and both ends of the path are larger than those in the Y axis path, and the Y direction residual stress curves parallel to the Y axis path are of "W" type. The Z direction residual stress parallel to the Z axis path decreases gradually from the bottom to the top of the deposited part, that is, it is easy to crack between the substrate and the deposited part.
【學(xué)位授予單位】：華東交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB333

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 付永信;王建江;杜心康;張龍;葉明惠;;熱噴涂技術(shù)制備功能梯度材料涂層的發(fā)展?fàn)顩r[J];材料保護(hù);2006年06期

2 凌云漢,白新德,李江濤,葛昌純;W/Cu功能梯度材料的熱應(yīng)力優(yōu)化設(shè)計(jì)[J];稀有金屬材料與工程;2003年12期

3 高靜;劉穎;李軍;馬毅龍;杜慧龍;高升吉;;化學(xué)氣相沉積法制備Nd-Fe-B/α-Fe納米復(fù)合磁體[J];稀有金屬材料與工程;2010年06期

相關(guān)博士學(xué)位論文 前3條

1 周躍亭;功能梯度材料中界面裂紋對彈性波的散射及熱斷裂問題[D];上海交通大學(xué);2007年

2 趙懷瑞;高速列車外形多學(xué)科設(shè)計(jì)優(yōu)化關(guān)鍵技術(shù)研究[D];北京交通大學(xué);2012年

3 袁華;碳纖維增強(qiáng)受電弓滑板的制備與性能及摩擦磨損機(jī)理的研究[D];山東大學(xué);2013年

本文編號：2023915