本文選題：高強(qiáng)度鋼材　切入點(diǎn)：焊接節(jié)點(diǎn)　出處：《清華大學(xué)》2015年博士論文

【摘要】：高強(qiáng)度鋼材以其顯著的優(yōu)勢(shì)在國內(nèi)外實(shí)際工程中得到了成功應(yīng)用,但應(yīng)用中仍面臨低溫冷脆、屈強(qiáng)比增大、延性降低和焊接連接等問題。本文基于高強(qiáng)度鋼材的斷裂微觀機(jī)理,以大量的試驗(yàn)研究為基礎(chǔ),結(jié)合數(shù)值計(jì)算和理論分析,從材料材性、典型構(gòu)造和梁柱節(jié)點(diǎn)三個(gè)層面對(duì)高強(qiáng)度鋼材鋼結(jié)構(gòu)的斷裂性能展開了系統(tǒng)研究,主要研究工作和成果如下:(1)對(duì)國產(chǎn)高強(qiáng)度結(jié)構(gòu)鋼材及其對(duì)接焊縫共計(jì)120個(gè)材性試件進(jìn)行了一系列的低溫拉伸、沖擊、三點(diǎn)彎斷裂韌性及電鏡掃描試驗(yàn),系統(tǒng)研究了高強(qiáng)度焊接鋼材在低溫下的力學(xué)性能、韌性性能及斷裂微觀機(jī)理,分析了鋼材強(qiáng)度對(duì)其斷裂性能的影響,為高強(qiáng)鋼結(jié)構(gòu)選材和考慮低溫的防脆斷設(shè)計(jì)提供了豐富的材性數(shù)據(jù)。(2)基于微觀機(jī)理提出斷裂預(yù)測(cè)模型,通過54個(gè)缺口圓棒和12個(gè)光滑圓棒的單調(diào)拉伸和低周疲勞試驗(yàn),結(jié)合有限元分析,建立了460MPa高強(qiáng)度鋼材及其焊縫的單調(diào)拉伸及循環(huán)本構(gòu)模型,標(biāo)定了微觀機(jī)理模型中的材料韌性參數(shù),以及循環(huán)荷載下的損傷退化系數(shù)。結(jié)果表明韌性參數(shù)與屈強(qiáng)比沒有明顯關(guān)聯(lián),而與塑性指標(biāo)存在一定關(guān)系。研究為后續(xù)高強(qiáng)鋼結(jié)構(gòu)節(jié)點(diǎn)的斷裂性能分析提供了必要基礎(chǔ)。(3)選取代表實(shí)際梁柱節(jié)點(diǎn)局部焊接構(gòu)造的典型十字型焊接接頭試件,采用對(duì)接熔透焊和角焊縫兩種焊縫類型,完成了20個(gè)高強(qiáng)度鋼材典型焊接節(jié)點(diǎn)在單調(diào)拉伸和往復(fù)加載下的斷裂性能試驗(yàn),探討了焊縫類型、荷載類型及鋼材強(qiáng)度對(duì)其斷裂性能的影響,為發(fā)展高強(qiáng)度鋼材焊接節(jié)點(diǎn)的斷裂分析模型提供了依據(jù)。(4)完成了4個(gè)高強(qiáng)鋼框架栓-焊混接梁柱節(jié)點(diǎn)足尺試件的往復(fù)加載試驗(yàn),包括4種不同的構(gòu)造細(xì)節(jié),分析了焊接工藝細(xì)節(jié)及節(jié)點(diǎn)局部構(gòu)造對(duì)高強(qiáng)鋼框架梁柱節(jié)點(diǎn)低周疲勞斷裂性能的影響,得到相應(yīng)節(jié)點(diǎn)試件斷裂性能指標(biāo),為發(fā)展適用于強(qiáng)震作用下高強(qiáng)度鋼結(jié)構(gòu)梁柱節(jié)點(diǎn)的高應(yīng)變低周疲勞斷裂預(yù)測(cè)模型提供了依據(jù)。(5)基于本文中高強(qiáng)鋼典型焊接接頭和高強(qiáng)鋼框架梁柱節(jié)點(diǎn)的試驗(yàn)研究,建立了節(jié)點(diǎn)精細(xì)化有限元模型,應(yīng)用微觀機(jī)理模型和結(jié)構(gòu)多尺度模型相結(jié)合的斷裂預(yù)測(cè)模型對(duì)高強(qiáng)鋼梁柱節(jié)點(diǎn)的低周疲勞斷裂性能進(jìn)行了分析。研究驗(yàn)證了微觀機(jī)理模型對(duì)于高強(qiáng)鋼梁柱節(jié)點(diǎn)延性斷裂預(yù)測(cè)的有效性,以及模型對(duì)于不同幾何構(gòu)造的普遍適用性,為高強(qiáng)鋼結(jié)構(gòu)節(jié)點(diǎn)的低周疲勞斷裂分析提供了一種有效分析方法。
[Abstract]:High strength steel has been successfully applied in practical engineering at home and abroad with its remarkable advantages. However, the application still faces the problems of low temperature cold embrittlement, increasing yield ratio, decreasing ductility and welding connection, etc. This paper is based on the fracture microscopic mechanism of high strength steel. Based on a large number of experimental studies, combined with numerical calculation and theoretical analysis, the fracture properties of high strength steel structures are systematically studied from three aspects: material properties, typical structures and Liang Zhu joints. The main research work and results are as follows: (1) A series of low-temperature tensile tests, impact tests, three-point bending fracture toughness and scanning electron microscopy tests were carried out on 120 domestic high strength structural steels and their butt welds. The mechanical properties, toughness properties and fracture micromechanism of high strength welded steel at low temperature were studied systematically. The influence of steel strength on fracture properties was analyzed. This paper provides abundant material data for material selection of high strength steel structure and brittleness resistance design considering low temperature. Based on microscopic mechanism, a fracture prediction model is proposed. Through monotonic tensile and low cycle fatigue tests of 54 notched round rods and 12 smooth round bars, Combined with finite element analysis, the monotone tensile and cyclic constitutive models of 460MPa high strength steels and their welds are established, and the material toughness parameters in the microscopic mechanism model are calibrated. And the damage degradation coefficient under cyclic load. The results show that there is no obvious correlation between the toughness parameter and the yield ratio. The study provides a necessary basis for the subsequent analysis of fracture properties of high-strength steel structure joints. The typical cross-welded joint specimens, which represent the local welding structure of Liang Zhu joints, are selected. The fracture behavior tests of 20 typical welded joints of high strength steel under monotonic tensile and reciprocating loading were carried out by means of butt penetration welding and fillet weld, and the weld types were discussed. The effect of load type and steel strength on the fracture properties of high strength steel welded joints provides a basis for the development of fracture analysis model of high strength steel welded joints. The reciprocating loading tests of four full-scale specimens of high strength steel frame bolt-welded mixed Liang Zhu joints have been completed. Including four different structural details, the effects of welding process details and joint local structure on the low cycle fatigue fracture properties of Liang Zhu joints of high strength steel frames are analyzed, and the fracture performance indexes of the corresponding joints are obtained. In order to develop a prediction model of high strain and low cycle fatigue fracture for Liang Zhu joints of high strength steel structures under strong earthquake, the experimental study on typical welded joints of high strength steel and Liang Zhu joints of high strength steel frames in this paper is presented. The fine finite element model of node is established. The low cycle fatigue fracture behavior of Liang Zhu joints of high strength steel was analyzed by using the fracture prediction model combined with micro mechanism model and multi scale structural model. The validity of sexual fracture prediction, The universal applicability of the model to different geometric structures provides an effective analysis method for low-cycle fatigue fracture analysis of joints of high-strength steel structures.
【學(xué)位授予單位】：清華大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU511.3
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本文編號(hào)：1690935