樹脂基復(fù)合材料鉆削缺陷產(chǎn)生機(jī)理與控制策略研究
發(fā)布時(shí)間：2019-01-07 19:12
【摘要】：碳纖維增強(qiáng)樹脂基復(fù)合材料(CFRP)因其良好的綜合性能在航空航天領(lǐng)域得到了廣泛的應(yīng)用。CFRP構(gòu)件與其他航空結(jié)構(gòu)件裝配時(shí),大都需要鉆削、銑削等后續(xù)機(jī)械加工方式,以滿足裝配的精度要求,其中鉆削占后續(xù)機(jī)械加工總量的50%以上。然而,CFRP具有硬度高、層間結(jié)合強(qiáng)度低和各向異性等特點(diǎn),使其成為典型的難加工材料。在CFRP鉆削加工中,以分層、撕裂、毛刺等為代表的加工缺陷,嚴(yán)重制約了CFRP構(gòu)件的整體性能和服役壽命。在當(dāng)前的研究中,尚缺乏針對(duì)CFRP加工缺陷形成及抑制的有效理論支撐與系統(tǒng)方法。因此,研究CFRP鉆削加工缺陷形成機(jī)理,構(gòu)建加工缺陷控制理論支撐體系,建立加工缺陷控制策略,已成為CFRP加工研究領(lǐng)域值得關(guān)注的課題。本文以CFRP為研究對(duì)象,研究加工缺陷在切削力與切削熱作用下的擴(kuò)展機(jī)制與控制策略。首先針對(duì)以分層為代表的CFRP加工缺陷,創(chuàng)新地應(yīng)用“研磨觀察法”對(duì)分層的三維形貌進(jìn)行了觀察,結(jié)合不同鉆削深度試驗(yàn)得到了鉆削過程中分層的變化趨勢(shì),并發(fā)現(xiàn)了“隱性分層區(qū)”的存在。進(jìn)而利用cohesive單元進(jìn)行復(fù)合材料切削微觀尺度有限元建模,分析不同鋪層角度的纖維斷裂形式。最終從理論角度對(duì)復(fù)合材料加工缺陷進(jìn)行分析,得出力與溫度對(duì)缺陷產(chǎn)生與擴(kuò)展的重要影響,為后續(xù)的切削力與切削溫度分析奠定基礎(chǔ)。切削溫度對(duì)CFRP的性能具有直接的影響。針對(duì)切削溫度對(duì)CFRP加工缺陷的影響,對(duì)切削加工過程中的溫度分布特性及對(duì)表面質(zhì)量的影響進(jìn)行分析。借助傳熱學(xué)對(duì)高速運(yùn)動(dòng)線熱源溫度場(chǎng)進(jìn)行研究,分析不同鋪層角度CFRP的散熱性能。利用半人工熱電偶測(cè)溫方法進(jìn)行切削溫度驗(yàn)證試驗(yàn),并利用SEM分析0。、90。鋪層的復(fù)合材料在玻璃化轉(zhuǎn)變溫度前后加工質(zhì)量的變化。最后分析不同切削溫度條件下切削力對(duì)CFRP加工質(zhì)量的影響,指出了玻璃化轉(zhuǎn)變溫度在CFRP切削加工中的重要影響。對(duì)CFRP的切削力進(jìn)行精確的理論預(yù)測(cè),是對(duì)加工缺陷進(jìn)行控制的前提。基于CFRP的力學(xué)性質(zhì),利用試驗(yàn)觀察分析不同鋪層角度條件下的CFRP斷裂特征,并將其斷裂過程分為彎曲切斷及彎曲折斷兩種形式。借助接觸力學(xué)、復(fù)合材料力學(xué)、斷裂力學(xué)等相關(guān)理論,根據(jù)CFRP在切削過程中纖維變形區(qū)、前刀面滑移區(qū)與后刀面回彈區(qū)的受力情況,建立描述各區(qū)域的切削分力數(shù)學(xué)模型,實(shí)現(xiàn)CFRP切削力的有效預(yù)測(cè),并進(jìn)行了切削力模型的試驗(yàn)驗(yàn)證。通過切削力理論預(yù)測(cè)模型的構(gòu)建,為CFRP加工缺陷控制策略提供理論支撐�；贑FRP的切削溫度與切削力分析,進(jìn)行CFRP加工缺陷控制策略研究,首先根據(jù)切削力理論預(yù)測(cè)模型完成CFRP鉆削刀具前角、后角對(duì)切削力的影響分析,通過增強(qiáng)刀具的鋒利性,實(shí)現(xiàn)了對(duì)毛刺及撕裂缺陷的有效控制,并進(jìn)行了相應(yīng)的驗(yàn)證試驗(yàn)；進(jìn)而根據(jù)鉆頭三維結(jié)構(gòu),完成鉆頭頂角對(duì)單位長度切削刃軸向力影響分析,通過優(yōu)化頂角實(shí)現(xiàn)了刀具壽命的有效提高。針對(duì)改進(jìn)結(jié)構(gòu)的鉆頭,結(jié)合切削力與切削溫度的影響,利用響應(yīng)曲面法完成了以鉆削軸向力與鉆削溫度為優(yōu)化目標(biāo)的加工參數(shù)優(yōu)化分析,利用最優(yōu)參數(shù)進(jìn)行刀具壽命對(duì)比試驗(yàn),驗(yàn)證了優(yōu)化刀具壽命提高的可靠性。
[Abstract]:The carbon fiber reinforced resin-based composite (CFRP) has been widely used in the field of aerospace because of its good comprehensive properties. When the CFRP member is assembled with other aviation structural members, the following mechanical processing methods such as drilling, cutting and the like are required to meet the accuracy requirement of assembly, wherein the drilling amount is more than 50% of the total amount of the subsequent machining. However, the CFRP has the characteristics of high hardness, low bonding strength between layers and anisotropy, and makes it a typical hard-working material. The whole performance and service life of the CFRP component are seriously restricted by the processing defects such as delamination, tearing, burr and the like in the processing of the CFRP drilling. In the present study, there is a lack of effective theoretical support and system methods for the formation and suppression of the defects of CFRP processing. Therefore, to study the formation mechanism of the processing defect of CFRP drilling, to build the support system of machining defect control, and to set up the control strategy of machining defect, it has become a subject of attention in the research field of CFRP processing. In this paper, the extension mechanism and control strategy of the machining defects under the action of cutting force and cutting heat are studied by using CFRP as the research object. Firstly, aiming at the defects of CFRP processing represented by the layering, the three-dimensional morphology of the layered three-dimensional morphology was observed by using the 鈥済rinding and observation method鈥，
本文編號(hào)：2404034
[Abstract]:The carbon fiber reinforced resin-based composite (CFRP) has been widely used in the field of aerospace because of its good comprehensive properties. When the CFRP member is assembled with other aviation structural members, the following mechanical processing methods such as drilling, cutting and the like are required to meet the accuracy requirement of assembly, wherein the drilling amount is more than 50% of the total amount of the subsequent machining. However, the CFRP has the characteristics of high hardness, low bonding strength between layers and anisotropy, and makes it a typical hard-working material. The whole performance and service life of the CFRP component are seriously restricted by the processing defects such as delamination, tearing, burr and the like in the processing of the CFRP drilling. In the present study, there is a lack of effective theoretical support and system methods for the formation and suppression of the defects of CFRP processing. Therefore, to study the formation mechanism of the processing defect of CFRP drilling, to build the support system of machining defect control, and to set up the control strategy of machining defect, it has become a subject of attention in the research field of CFRP processing. In this paper, the extension mechanism and control strategy of the machining defects under the action of cutting force and cutting heat are studied by using CFRP as the research object. Firstly, aiming at the defects of CFRP processing represented by the layering, the three-dimensional morphology of the layered three-dimensional morphology was observed by using the 鈥済rinding and observation method鈥，
本文編號(hào)：2404034
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