基于有限元分析的板料形状对S梁拉深的影响

基于DYNAFORM动力显式有限元分析软件,将数值模拟技术应用于S梁的坯料优化过程,研究了不同的毛坯形状、尺寸对S梁拉深的成形极限图、厚度分布、减薄率的影响。通过对比分析不同的坯料成形模拟结果,确定较为合理的毛坯形状尺寸。研究结果表明:方式1是不可取的,而方式2能很好地成形出合格零件,最大减薄率为16.6%,最大增厚率为1.84%。在法兰处可以适当添加拉延筋以缓解起皱趋势。     

Effect of Cyclic Loading on Cracking Behaviour of X-70 Pipeline Steel in Near-Neutral pH Solutions

The cracking behaviour of X-70 pipeline steel in near-neutral pH solutions was studied under different modes of cyclic loading. The crack propagation process of X-70 pipeline steel under low frequency cyclic loading condition was controlled mainly by stress corrosion cracking (SCC) mechanism. Under mixed-mode cyclic loading, both higher tensile stress and shear stress made cracks easier to propagate. Applied cathodic potentials and high content of carbon dioxide in solutions also promoted the propagation of cracks. The propagation directions of cracks were different under different cyclic loading conditions. Under mode I (pure tensile stress) cyclic loading condition, cracks were straight and perpendicular to the tensile stress axis, while under mixed-mode I/Ill (tensile/shear stress) cyclic loading, cracks were sinuous and did not propagate in the direction perpendicular to the main tensile stress axis. Under the mixed-mode cyclic loading, cracks were much easier to propagate, suggesting that shear stress intensified the role of tensile stress. In addition, shear stress promoted the interaction between cracks, resulting in easier coalescence of cracks.     

油气分离器失效分析

通过对油气分离器失效部位进行宏观检查、化学成分分析、金相分析、力学性能测试、断口形貌观察及能谱分析,认为工艺介质中硫化氢浓度的上升和材料纯净度不高是导致设备失效的根本原因,并提出了相应的建议。     

A statistical micromechanical model of multiple cracking for ultra high toughness cementitious composites

A new statistical micromechanical model of multiple cracking is proposed in which a general expression of the fiber bridging stress laws in the crack plane is established. In this model, the random distribution properties of fibers are considered. And the Weibull function is adopted to represent the flaw size distribution. The relationships of stress versus strain and crack width versus strain are proposed. The formulas of the crack width, crack space, strain capacity and fracture energy density at the end of multiple cracking processes are also deduced. The validity of the proposed model was demonstrated by experimental results.     

The effect of roll-processing orientation on stress corrosion cracking of warm-rolled 304L stainless steel in oxygenated and deoxygenated high temperature pure water

Stress corrosion crack growth rates of 304L stainless steel after one-directionally warm-rolled along the longitudinal (L) direction were measured in oxygenated and deoxygenated pure water at 288 °C. The fracture mode is mainly intergranular in the Transverse-longitudinal (T-L) orientation specimen, while it is occasionally intergranular in the Longitudinal-transverse (L-T) orientation specimen. The crack growth rates in the T-L orientation are higher than those in the L-T orientation in both oxygenated and deoxygenated environments, which is related to the effective cracking growth path as the result of microstructural anisotropy and applied loading direction.     

高腐蚀率钢筋混凝土梁抗弯性能研究

对4根未腐蚀和16根腐蚀钢筋混凝土梁进行抗弯试验,研究重复荷载下高腐蚀率对钢筋混凝土梁变形、裂缝、承载力及破坏机理的影响。提出重复荷载下受腐蚀钢筋混凝土梁承载力计算公式。同时拟合出钢筋腐蚀率对钢筋混凝土受弯开裂的影响,并提出受腐蚀梁在重复荷载下的开裂荷载计算公式。     

FCC废催化剂镁改性催化裂化性能再生研究

提出并证实了高的强酸性位可接近性导致FCC废催化剂失活的机制。基于所提出的失活机制,采用浸渍法对FCC废催化剂进行镁改性再生。对所制备的再生FCC废催化剂进行了表征并考察了其重油催化裂化性能。表征结果表明,与未改性的FCC废催化剂相比,再生FCC废催化剂表面酸强度被一定程度地削弱,而表面总酸量和结构性质参数未出现显著改变。重油催化裂化结果表明,得益于适宜的表面酸性,再生FCC废催化剂的催化裂化反应性能得到极大改善。与未改性的FCC废催化剂相比,再生FCC废催化剂的汽油产率显著增加了3.04个百分点,同时干气、液化气、焦炭和重油产率则分别下降了0.36、0.81、1.28和0.87个百分点,这使得所制备的再生FCC废催化剂可以代替部分新鲜FCC催化剂使用。最后,探讨了再生FCC废催化剂表面酸性改变机理。     

含磷模板和不同硅源对多级孔ZSM-5分子筛结构和催化性能的影响

通过采用不同比例的四丁基氢氧化磷（TBPOH）和四丙基氢氧化铵（TPAOH）混合作为模板剂合成多级孔ZSM-5分子筛,采用XRD,BET,SEM,TEM,NH3-TPD,MAS NMR等方法对分子筛进行物化表征,考察TPAOH和TBPOH的协同作用,期望得到较高结晶度的含P的多级孔ZSM-5。结果表明：以正硅酸乙酯（TEOS）为硅源,在TBPOH和TPAOH物质的量比为1∶1时,合成的多级孔ZSM-5形貌较为规整,由ZSM-5小晶粒堆积而成并呈现出丰富的介孔结构,具有较大的比表面积和孔体积,平均孔径分布于4～10 nm和50～70 nm。相比常规ZSM-5分子筛,合成的多级孔ZSM-5分子筛表现出更强的弱酸性和更多的总酸量。在1,3,5-三异丙苯的裂解反应中,相同转化率下,微孔ZSM-5分子筛表现出较好的苯和二异丙苯的选择性,而多级孔ZSM-5表现出更加优异的丙烯和异丙苯的选择性。     

丙烷裂解与丙烷脱氢路线技术经济及安全性分析

液化气中丙烷既可作为优质烯烃裂解原料也可脱氢增产丙烯。以320 kt/a原料处理规模的丙烷裂解和丙烷脱氢工艺为考察对象,分别采用Aspen Plus软件进行了丙烷裂解及丙烷脱氢两种工艺流程模拟及工艺参数优化,通过提取原料消耗、公用工程消耗、工艺操作参数、化学品特性等信息进行技术经济安全性比较;若丙烷裂解以双烯（乙烯和丙烯）、丙烷脱氢以丙烯作为产品,两种工艺的产品收率分别为80.3%和84.4%,产品能耗为4.6 MW/t、4.4 MW/t;丙烷裂解与丙烷脱氢火灾爆炸指数（F&EI）最大的设备分别为裂解炉和丙烯精馏塔,F&EI分别为185.6和125.7。