鋼結構管桁架疲勞損傷的解決措施
發布時間:2014-07-15
改變網架鋼結構中的拉伸殘餘應力,有不少T藝方法和工藝措施。其中用得最多的是回火處理T藝,即將構件整體放入高溫爐中加熱,一般加熱到600~800。C,之(zhi)後(hou)再(zai)均(jun)勻(yun)地(di)逐(zhu)步(bu)冷(leng)卻(que)。由(you)於(yu)加(jia)熱(re)和(he)冷(leng)卻(que)過(guo)程(cheng)中(zhong)結(jie)構(gou)變(bian)形(xing)的(de)均(jun)勻(yun)整(zheng)體(ti)化(hua),從(cong)而(er)使(shi)局(ju)部(bu)過(guo)高(gao)的(de)殘(can)餘(yu)應(ying)力(li)和(he)應(ying)變(bian)得(de)到(dao)鬆(song)弛(chi)。對(dui)大(da)型(xing)構(gou)件(jian)來(lai)說(shuo),這(zhe)種(zhong)方(fang)法(fa)要(yao)求(qiu)有(you)很(hen)大(da)尺(chi)度(du)的(de)高(gao)溫(wen)加(jia)熱(re)裝(zhuang)置(zhi),因(yin)此(ci),能(neng)處(chu)理(li)構(gou)件(jian)的(de)尺(chi)度(du)受(shou)實(shi)際(ji)加(jia)熱(re)裝(zhuang)置(zhi)設(she)備(bei)的(de)限(xian)製(zhi)。
在早期鋼結構橋梁的製造過程中,其重要的焊接部位使用過手工敲擊,或用氣動的劈槍進行敲擊等方法,試圖減少焊接部位的殘餘應力、以(yi)便(bian)提(ti)高(gao)結(jie)構(gou)疲(pi)勞(lao)壽(shou)命(ming)。但(dan)手(shou)工(gong)敲(qiao)擊(ji)的(de)頻(pin)度(du)很(hen)低(di),輸(shu)入(ru)到(dao)結(jie)構(gou)中(zhong)的(de)能(neng)量(liang)有(you)限(xian),因(yin)此(ci)效(xiao)果(guo)不(bu)顯(xian)著(zhu)。在(zai)一(yi)些(xie)金(jin)屬(shu)加(jia)工(gong)製(zhi)造(zao)業(ye),由(you)於(yu)一(yi)些(xie)要(yao)部(bu)件(jian)的(de)加(jia)工(gong)裝(zhuang)配(pei)精(jing)度(du)要(yao)求(qiu)日(ri)益(yi)提(ti)高(gao),降(jiang)低(di)構(gou)件(jian)殘(can)餘(yu)應(ying)力(li)、提(ti)高(gao)構(gou)件(jian)使(shi)用(yong)壽(shou)命(ming)的(de)要(yao)求(qiu)更(geng)為(wei)迫(po)切(qie),從(cong)而(er)發(fa)展(zhan)了(le)一(yi)種(zhong)稱(cheng)為(wei)高(gao)速(su)噴(pen)丸(wan)的(de)技(ji)術(shu),其(qi)效(xiao)果(guo)十(shi)分(fen)顯(xian)著(zhu),能(neng)明(ming)顯(xian)地(di)提(ti)高(gao)疲(pi)勞(lao)性(xing)能(neng)和(he)抗(kang)應(ying)力(li)腐(fu)蝕(shi)的(de)能(neng)力(li)並(bing)獲(huo)得(de)了(le)廣(guang)泛(fan)的(de)應(ying)用(yong)。為(wei)提(ti)高(gao)敲(qiao)擊(ji)的(de)頻(pin)率(lv)和(he)能(neng)量(liang),進(jin)一(yi)步(bu)研(yan)究(jiu)使(shi)用(yong)振(zhen)動(dong)方(fang)法(fa)來(lai)降(jiang)低(di)結(jie)構(gou)的(de)殘(can)餘(yu)應(ying)力(li)。對(dui)尺(chi)度(du)不(bu)大(da)的(de)部(bu)件(jian)或(huo)零(ling)件(jian),可(ke)將(jiang)其(qi)直(zhi)接(jie)安(an)裝(zhuang)在(zai)振(zhen)動(dong)台(tai)上(shang)進(jin)行(xing)激(ji)振(zhen)。
研(yan)究(jiu)表(biao)明(ming),振(zhen)動(dong)台(tai)上(shang)的(de)高(gao)頻(pin)能(neng)量(liang)輸(shu)入(ru)到(dao)金(jin)屬(shu)構(gou)件(jian)中(zhong),對(dui)鬆(song)弛(chi)構(gou)件(jian)中(zhong)的(de)殘(can)餘(yu)虛(xu)力(li)有(you)一(yi)定(ding)的(de)效(xiao)果(guo)。由(you)於(yu)高(gao)頻(pin)振(zhen)動(dong)台(tai)的(de)尺(chi)度(du)有(you)限(xian),因(yin)此(ci)隻(zhi)能(neng)對(dui)尺(chi)度(du)不(bu)大(da)的(de)構(gou)件(jian)采(cai)用(yong)這(zhe)種(zhong)方(fang)法(fa)。對(dui)尺(chi)度(du)較(jiao)大(da)的(de)結(jie)構(gou),可(ke)在(zai)重(zhong)要(yao)的(de)焊(han)接(jie)件(jian)上(shang)采(cai)用(yong)局(ju)部(bu)振(zhen)動(dong)的(de)方(fang)法(fa)。這(zhe)種(zhong)方(fang)法(fa)的(de)難(nan)度(du)在(zai)於(yu),既(ji)要(yao)求(qiu)作(zuo)用(yong)在(zai)結(jie)構(gou)焊(han)縫(feng)區(qu)振(zhen)動(dong)器(qi)的(de)尺(chi)寸(cun),又(you)必(bi)須(xu)要(yao)有(you)足(zu)夠(gou)的(de)質(zhi)量(liang)和(he)很(hen)高(gao)的(de)振(zhen)動(dong)作(zuo)用(yong)頻(pin)率(lv),因(yin)為(wei)輸(shu)入(ru)到(dao)金(jin)屬(shu)結(jie)構(gou)件(jian)中(zhong)的(de)能(neng)量(liang)是(shi)與(yu)振(zhen)43動器的質量和作用頻率平方的乘積成正比。
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