摘 要:作為顆粒材料去強化基體材料是準晶的重要應(yīng)用之一,因此研究基體和夾雜(微小顆粒材料可看成是夾雜)界面剛性線問題具有重要的理論和現(xiàn)實意義?;趶?fù)變函數(shù)方法,研究了平面集中力和無限遠處均勻拉伸應(yīng)力作用下,含界面剛性線的圓形準晶夾雜的三維二十面體準晶平面彈性問題,得到應(yīng)力分量和位移分量的封閉解,給出了剛性線夾雜尖端奇異應(yīng)力場的解析表達式。數(shù)值計算討論了耦合系數(shù)、夾雜半徑和相位子場彈性常數(shù)對應(yīng)力奇異因子的影響。結(jié)果表明:在平面載荷作用下,圓弧形剛性線尖端的應(yīng)力場具有奇異性;夾雜半徑對應(yīng)力奇異因子的影響大于耦合系數(shù)以及相位子場參數(shù)對應(yīng)力奇異因子的影響。
關(guān)鍵詞:準晶;圓形夾雜;剛性線;復(fù)變函數(shù)方法;應(yīng)力奇異因子
中圖分類號:O753.3" 文獻標志碼:A
文章編號:1000-4939(2025)01-0081-
10
The plane elasticity problem of circular arc interface rigid lines in three-dimensional icosahedral quasicrystals
ZHAI Ting1,MA Yuanyuan1,ZHAO Xuefen2
(1.School of Mathematical Statistics,Ningxia University,750021 Yinchuan,China;
2.Xinhua College,Ningxia University,750021 Yinchuan,China)
Abstract:It is one of the important applications of quasicrystals to strengthen matrix materials as granular materials.Therefore,it is of great theoretical and practical significance to study the interface rigid line between matrix and inclusions (micro granular materials can be regarded as inclusions).Based on the method of complex function,the plane elasticity problem of three-dimensional icosahedral quasicrystals with circular rigid line inclusions under the action of plane concentrated force and infinite uniform tensile stress is studied.The closed solutions of stress and displacement components in several typical cases are obtained,and the analytical expressions of singular stress field at the tip of rigid line inclusion are given.The effects of the radius of inclusion and coupling coefficient on the stress singularity factor are discussed numerically.The results show that the stress field at the tip of the circular rigid line inclusion has singularity under the plane load,and the influence of the radius of the inclusion on the stress singularity factor is greater than that of the coupling coefficient and phase field elastic constant.
Key words:quasicrystal; circular inclusion; rigid line; complex function method; stress singularity factor
準晶是1984年發(fā)現(xiàn)的一種新型結(jié)構(gòu)和固體材料。由于獨特的結(jié)構(gòu),使得準晶材料具有一些新的物理性質(zhì)與化學(xué)性質(zhì)特征,如耐磨、低密度、高硬度、抗氧耐腐、耐高溫等[1-3]。準晶材料在室溫呈脆性[4-6],而脆性材料對缺陷非常敏感。孟祥敏等[7]的實驗揭示了準晶體在外載荷、熱載荷和一定內(nèi)部效應(yīng)作用下是可變形的,這使得它對裂紋、夾雜等缺陷非常敏感。因此,研究準晶材料的界面缺陷問題有重要的理論意義和實際應(yīng)用價值。
作為顆粒材料去強化基體材料是準晶的重要應(yīng)用之一,基于此,研究準晶材料的夾雜問題顯得尤為重要。利用廣義復(fù)變函數(shù)法,WANG等[8]討論了一維正方準晶中裂紋和剛性線夾雜問題?;诔娈惙e分方程,LOU等[9]討論了無限一維六方準晶體中嵌入薄彈性夾雜的模型,用數(shù)值方法給出了應(yīng)力強度因子的解。通過構(gòu)造新的保角映射,GUO等[10]分析了無限大一維六方壓電準晶基體中內(nèi)嵌橢圓夾雜的問題。HU等[5]研究了一維壓電準晶材料中的部分脫黏圓形夾雜模型,得到了聲子場、相位子場的應(yīng)力強度因子及電場的電位移強度因子。ZHANG等[11]研究了3種不同外載荷作用下的含球狀夾雜一維六方壓電準晶體的彈性問題。WANG[12]基于解析延拓和保角變換研究了含任意形狀夾雜二維十次對稱準晶的Eshelby問題。馬園園等[13]研究了點熱源作用下十二次二維對稱準晶基體和圓形準晶夾雜界面之間含多個裂紋的問題。WANG等[14]求得了熱流作用下含橢圓夾雜的二維十次準晶的溫度場、聲子場和相位子場的場變量解析解。
與一維和二維準晶相比,三維準晶本身的耦合特性,物理和幾何性質(zhì)更加復(fù)雜,這就使得三維準晶夾雜問題的求解更加困難。張亮亮[15]基于Stroh理論,研究了三維立方準晶含橢圓夾雜的問題。WANG等[16]研究了三維二十面體準晶中球形夾雜中問題,獲得了聲子場和相位子場的一階近似解析表達式。界面剛性線是一種硬質(zhì)夾雜,在剛性線尖端會發(fā)生嚴重的應(yīng)力集中現(xiàn)象,造成材料破壞。查閱文獻發(fā)現(xiàn),目前還未有學(xué)者對三維二十面體準晶剛性線夾雜相關(guān)問題進行研究。本研究基于復(fù)變函數(shù)方法研究了三維二十面體準晶在集中力和無窮遠均勻拉伸作用下含界面圓弧剛性線夾雜的平面彈性問題,得到了幾種特殊情況下應(yīng)力分量和位移分量的封閉解,給出了剛性線夾雜尖端奇異應(yīng)力場因子的解析表達式。數(shù)值計算討論了耦合系數(shù)、夾雜半徑和相位子場彈性常數(shù)對應(yīng)力奇異因子的影響。
1 基本方程和問題描述
根據(jù)準晶線彈性理論,三維二十面體準晶的廣義胡克定律[17]可以表示成
圖4~圖5繪制了R/μ取不同值時,剛性線角度α對剛性線尖端b的應(yīng)力奇異因子影響。從圖中可以觀察到,在無窮遠加載作用下,無量綱應(yīng)力奇異因子S10隨剛性線角度α的增大而增加,在α=80°附近達到最大值,之后隨著α的增大而減小,在
α=144°附近達到最小值,隨后再增加。而無量綱應(yīng)力奇異因子S20先隨α的增大而減小,在α=85°附近達到最小值,然后隨α的增大而增大,在α=170°附近時達到最大值后再減小。從破壞機理來看,無窮遠載荷作用下剛性線角度α=50°時最容易發(fā)生破壞。
圖6~圖7給出了夾雜半徑r不同時無量綱應(yīng)力奇異因子隨剛性線角度α的變化情形。
從圖中可以觀察到夾雜半徑r的大小對裂紋尖端應(yīng)力奇異因子有很明顯的影響,r越大,應(yīng)力場奇異因子的變化趨勢越明顯且絕對值越大。S10開始隨剛性線角度α增大而增大,在α=80°附近達到最大值,然后隨α進一步增大而減小,之后再增大。而S20先隨剛性線角度α增大而減小,當剛性線角度α在90°附近時應(yīng)力奇異因子S20最小,之后S20隨著α增大而增大,在160°附近S20達到最大正值。
圖8~圖9描述了相位子場參數(shù)K(1)1取不同值時無量綱應(yīng)力奇異因子隨剛性線角度α的變化情形。
由圖可知,相位子場參數(shù)K(1)1越小,應(yīng)力奇異因子的變化趨勢越明顯,絕對值越大。如圖8所示,S10先隨著α的增大而增大,在70°附近達到最大值,這表明此處剛性線對界面的破壞達到最大。之后,隨著α的增大逐漸減小且在α=145°附近達到最小值,這表明當70°lt;αlt;150°時,剛性線對S10的相互屏蔽作用逐漸減小。S20隨著剛性線角度α的增大而減小,當剛性線角度α接近100°,S20達到最小值,然后隨著α的增加再增加,在α接近170°時取到最大正值。圖9表明當0°lt;αlt;100°時,剛性線對S20的相互屏蔽作用逐漸減小,此時界面破壞主要由S10造成。當100°lt;αlt;170°時,剛性線對S20的相互放大作用單調(diào)增加,此時的界面破壞主要由S20造成。從圖4~圖9中可以看出,平面載荷作用下圓弧型剛性線尖端的應(yīng)力場具有奇異性,夾雜半徑對應(yīng)力奇異因子的影響顯著大于耦合系數(shù)以及相位子場參數(shù)對應(yīng)力奇異因子的影響。
6 結(jié)束語
基于復(fù)變函數(shù)方法,本研究把集中力作用下含界面剛性線的圓形夾雜三維二十面體準晶平面彈性問題轉(zhuǎn)化為解析函數(shù)邊值問題進行求解,導(dǎo)出了剛性圓弧夾雜在集中力作用下剛性線尖端應(yīng)力場奇異因子和應(yīng)力場的解析表達式。數(shù)值分析給出了耦合系數(shù)、夾雜半徑及相位子場參數(shù)對剛性線尖端應(yīng)力奇異因子的影響。本研究所得的結(jié)論可為準晶復(fù)合材料的優(yōu)化設(shè)計和制備提供一定的理論依據(jù)。
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(編輯 李坤璐)