高铝氧电瓷材料的破坏分析

本文研究了高铝氧电瓷材料的破坏机理。采用扫描电子显微镜(SEM)、电子探针(EDX)研究了高铝氧电瓷材料的断裂源、断裂过程、断裂形貌以及断裂源的成因,并用统计方法研究了断裂源不同的材料的强度分布规律。     

湿度对锦纶66帘线强伸性能的影响

进行了湿度对锦纶66帘线强伸性能影响的试验研究。通过统计分析断裂强力、断裂强力不匀率、定负荷伸长度、断裂伸长率、断裂伸长不匀率等旨标的试验数据并结合理论分析，得出随着相对湿度的增大，锦纶66帘线断裂强力下降，定负荷伸长率、断裂伸长率及断裂强力不匀率、断裂伸长不匀率增大的结论。     

解析柴达木盆地基底构造特征及其控油意义

柴达木盆地受祁连山和昆仑山的相向挤压控制,因此发育了柴北缘断裂、昆北断裂、祁连南缘断裂等区域性断裂构造。同时在阿尔金构造带的重大影响下,发育形成了阿南断裂、格尔木——锡铁山断裂等区域性构造。在两组不同方向上断裂构造的叠加作用力下,使柴达木中后期盆地呈现出北东——南西向以及北东——南西向分带的特征,同时在油气资源的形成、分布等方面产生重大的影响。     

拉萨地区重力场异常与断裂构造

本文以拉萨地区1：100万区域重力调查资料为依据,在对该资料进行处理与解释后,对该地区的重力异常的基本特征进行了研究。拉萨地区重力异常特征总体走向为近东西向,南部高、北部低,南部表现为重力梯级带特征,北部表现为宽大的重力低异常;通过对重力资料处理和分析,结合地质资料和其它地球物理资料,及其断裂构造在重力场上表现出的特征进行断裂识别,共识别出断裂19条（一级断裂4条、二级断裂9条、三级断裂6条）,其中的11条断裂是被首次发现,并对识别出的断裂中的几条主要断裂进行了综合解释;东西向断裂发育早、断距大、活动期长,将研究区划成了东西向的条带状结构,北东向和北西向断裂一般发育晚、断距较小,将东西向断裂进行了后期改造,使区内重力场明显具有南北成带、东西成块的基本特征。     

饶阳凹陷肃宁弧形断裂带成因与油气富集

弧形断裂是渤海湾盆地重要的油气富集带。本文利用肃宁地区三维地震资料、钻井、测井资料分析了该区新生代断裂活动性,并在此基础上探讨了弧形断裂活动对油气成藏的控制作用。研究认为,肃宁地区弧形断裂活动具有明显的阶段性,断裂活动对油气聚集规律具有重要的控制作用,主要表现在:断裂活动控制整个油气成藏过程,形成了形式多样的油气藏类型。     

钢纤维砂浆纳米压痕微观断裂性能表征

钢纤维砂浆为多相复合材料,传统宏观试验方法难以表征其中各相的微观断裂参数,因此无法明确材料宏观断裂性能的微观机理。基于纳米压痕技术,研究了钢纤维砂浆中主要组成相的微观断裂性能。根据压痕能量法基本原理和加载、卸载过程的荷载—位移曲线特征,建立了考虑持荷作用的塑性能显式计算公式。通过该式和压痕曲线能够直接计算材料断裂能、能量释放率和断裂韧度。结果表明:基于纳米压痕技术的微观断裂研究方法能够得到稳定的净浆基体和石英砂的断裂韧度值,且该值与宏观断裂测试方法得到的断裂韧度数据一致,但低估了钢纤维的断裂韧度。该方法只适用于准脆性材料断裂性能的估算。     

甲乙酮反应器进料泵轴断裂失效分析

针对甲乙酮反应器进料泵轴断裂情况，通过材质检验，断口宏观特征观察及微观形貌分析，对其失效原因进行了分析。结果表明，泵轴材质化学成分、热处理状态、金相组织和力学性能符合相关标准规定，断裂呈脆性特征，断裂面具有对称性，且断裂面上存在疲劳断裂的3个特征区，其断裂是由双向弯曲应力作用下产生的疲劳断裂。     

面向微纳技术的液桥断裂研究进展

受尺度效应的影响，液桥的形态特征决定了液桥力的变化，液桥力的变化对液桥的形成与断裂具有重要影响。基于液桥形态学的液桥断裂机理是生物、化学、材料、微纳技术等研究领域的理论基础。目前，液桥断裂研究属于跨学科研究，涉及数学、流体力学、界面化学、材料学等学科，但较少有专注于液桥形态学的液桥断裂研究的综述。本综述总结了轴对称液桥、非轴对称液桥和非牛顿流体液桥的断裂理论模型和实验方法。首先，介绍了平衡或稳定状态下，液桥受迫拉伸、断裂过程中产生的流体弱非线性行为。其次，描述了液体体积、黏度、表面张力、表面润湿性和粗糙度、断裂速度、液桥形态等关键因素对液桥断裂位置或分配率的影响，归纳了研究影响液桥断裂参数时所采用的实验方法，讨论了不同实验装置的结构特征及其优缺点，总结并提出了该研究的创新特性和高价值的研究方向。最后，展望了微纳技术领域的液桥断裂的前沿研究方向，指出建立更全面的液桥断裂模型、研究多参数约束下的液桥断裂机理和控制方法是未来的研究重点。要点：(1)阐述了微尺度下液桥断裂研究的意义。(2)介绍了轴对称液桥，非轴对称液桥和非牛顿流体液桥的断裂机理、实验方法和研究进展。(3)描述了液体固有物理特性...     

高柳地区断裂特征研究

高柳地区主要受控于西南庄断裂、柏各庄断裂和高柳断裂，主控断裂的剖面形态主要为铲式；高柳地区Es3底界断裂的主要方位为NW向，Es1底部为界发育的断裂的主要方位为NEE向，方位存在明显差异；主控断裂的活动具分期性，控制了凹陷的形成、构造演化和沉积中心的转移，结合各断裂与油源的沟通能力，进而形成不同的地质特征。     

断裂控油气规律理论研究现状与进展

断裂构造是含油气盆地多种构造类型中最常见的一种,它不仅控制了盆地内沉积建造和层序发育,而且还直接或间接地控制着盆地内烃源岩、储集层、圈闭发育特征和油气的运移、聚集及油气藏的分布,只是不同级别不同性质的断裂在时空上对油气藏的形成和分布的控制作用则不相同。目前,关于断裂控油气规律的研究主要集中于断裂坡折带理论、断裂封闭性理论和断裂幕式活动理论三个方面,断裂坡折带理论集中研究同沉积断裂对沉积层序的控制,断裂封闭性理论和断裂幕式活动理论集中研究断裂活动与油气运聚关系的研究。     

UHMWPE结晶形态对冲击性能的影响

了超高分子量聚乙烯结晶形态对冲击性能的影响，模压烧结法制样，发现不同工艺条件制备的ＵＨＭＷ－ＰＥ制品的结晶形态差别很大，从而导致材料的抗冲击也截然不同，制品冲击强度取决于结晶度，晶体结构形态，工艺条件控制ＵＨＭＷＰＥ结晶形态为直径较粗大的类串晶形态，有利于提高制品的冲击性能。     

SMAH对PA6/ABS合金的增容作用研究

研究了(苯乙烯/马来酸酐)共聚物(SMAH)对尼龙(PA)6/(丙烯腈/丁二烯/苯乙烯)共聚物(ABS)合金的增容作用。运用红外光谱仪、毛细管流变仪和扫描电子显微镜等手段研究了SMAH增容的PA6/ABS合金的聚集态结构与性能。结果表明,PA6和ABS的简单共混体系的分散相容易聚集,断裂面呈岩石层状的脆性断裂形貌。而加入少量SMAH后的合金呈典型的"海-岛"结构,分散相分布均匀,断面呈现大量塑性变形的韧性断裂特征。     

几种复合材料的微观断裂行为研究

利用扫描电子显微镜对玻璃纤维增强尼龙１０１０、碳纤维增强尼龙１０１０、三元乙丙橡胶增韧尼龙６等几种复合材料断裂行为的观察，以及对导致材料破坏因素的讨论表明，增韧增强介质与基本树脂的粘结及分布将直接影响材料的力学性能，而力学性能的变化又将明显地反映在微观断裂形态上。     

聚硫密封剂浸油后拉伸断裂行为分析

研究了聚硫密封剂浸航空煤油后的断裂行为,对在3号航空煤油中浸渍不同时间(0、24、48、120、168h)的聚硫密封剂进行了拉伸性能测试,采用扫描电子显微镜,对拉伸断裂试样进行了断口观察,并对聚硫密封剂的断裂特征形成原因进行了分析.研究表明:密封剂拉伸时,裂纹形成、扩展到最后试样断裂,其过程可分为裂纹慢速扩展和快速断裂...     

The effect of chemical modification on the fracture toughness of montmorillonite clay/epoxy nanocomposites

The change in fracture toughness and its dependence on the content of clay nanoplatelets and adhesion at the interface between clay nanoplatelets and anhydride-cured epoxy matrix are discussed. Three clay nanoplatelets with different chemical modifications were used in this investigation. To fabricate nanocomposites, the clay nanoplatelets were sonicated in acetone for 2 h. The role of the clay nanoplatelets in the mechanical/fracture properties was investigated by transmission electron microscopy (TEM). Bright-field TEM micrographs showed excellent dispersion of clay nanoplatelets in epoxy matrix. Both intercalation and exfoliation of clay nanoplatelets were observed depending on clay modification. Compact tension specimens were used for fracture testing. The fracture toughness increased with increasing clay content. The fracture toughness of clay/epoxy nanocomposites varied with the clay morphology in the epoxy matrix. Different morphologies of the fracture surfaces, highly dependent on the morphology of dispersed clay nanoplatelets, were observed using environmental scanning electron microscopy (ESEM). The fracture toughness was found to be correlated with the fracture surface roughness measured by confocal laser scanning microscopy (CLSM).     

Plane strain fracture toughness of polyethylene pipe materials

The plane strain fracture toughness of medium density polyethylene pipe materials has been investigated over a range of test temperatures and rates. Conditions are defined under which valid fracture toughness values can be obtained; at higher temperatures the material is notch-insensitive. Fracture surface morphology is described, and features are compared with predictions from the Dugdale model. The toughness derives from a band of fibrillar, drawn morphology associated with crack initiation or slow growth. The plane strain fracture toughness correlates with percent crystallinity according to the same relationship whether the crystallinity is varied by thermal treatment, comonomer content, or molecular weight.     

Mechanisms of fatigue damage and fracture in semi-crystalline polymers

Fatigue crack profiles and fracture surfaces of poly(vinylidene fluoride) (PVDF), nylon-6,6 (N66), and poly(acetal) (PA) were studied to ascertain the mechanisms of cyclic damage and fatigue crack propagation in semicrystalline polymers. Crack tip damage is believed to begin as small trans-spherulitic and inter-spherulitic tensile crazes. However, compressive yielding within the reverse plastic zone at the crack tip crushes and elongates the spherulites in the direction of crack growth. Consequently, the microstructure of the polymer in advance of the crack front is different from the original morphology of the spherulitic bulk material as evidenced by the resulting fracture surface appearance. When the test temperature is below the glass transition temperature, however, plastic deformation is limited, and fatigue fracture occurs before significant disruption of the spherulitic structure. In this case, the fracture surface morphology reflects the original microstructure of the bulk polymer.     

Deformation modes and fatigue behavior in styrene-acrylonitrile and acrylonitrile-butadiene-styrene copolymers

The performance of styrene-acrylonitrile copolymers under alternating stresses has been examined. Information has been obtained concerning the influence of acrylonitrile content and of molecular weight on thermal effects due to hysteresis, on cyclic lifetime to craze initiation, on average cycles to fracture, and on fatigue fracture surface morphology. The influence of an elastomeric second phase has been determined by comparing fatigue performance under comparable conditions of both styrene-acrylonitrile (SAN) and acrylonitrile-butadiene-styrene (ABS). The stress concentrating effects of the rubber particles cause earlier initiation of fatigue-induced damage and lower fatigue fracture resistance. The fatigue-induced specimen temperature rise is greater in ABS than SAN and it increases linearly with test frequency and as the square of the stress amplitude. The fracture surface morphology of ABS, which differs from that of unmodified SAN and also from that of rubber modified polystyrene, is discussed.     

Correlation between nodular morphology and fracture properties of cured epoxy resins

Various bulk epoxy resin formulations, based on diglycidyl ether of bisphenol A (DGEBA) and cured with diethylene triamine (DETA) were studied. Methods of linear elastic fracture mechanics were employed and all systems were characterized by the corresponding values of the critical strain energy release rate for crack initiation and crack arrest. Fracture morphology was studied by scanning electron microscopy and transmission electron microscopy of carbon—platinum surface replicas. An apparent correlation between morphology and ultimate mechanical properties has been found. All fracture surfaces are shown to be characterized by distinct nodular morphology. Nodules, ranging in size from 15–45 nm, represent the sites of higher crosslink density in an inhomogeneous network structure. Fracture surfaces were further characterized by three crack propagation zones. A smooth, brittle fracture zone was preceded and followed by crack initiation and crack arrest zones, respectively. An apparent plastic flow was confined to the initiation and arrest regions. No crazing phenomenon was seen in the initiation zone; instead a step-like fracture was observed, typified by the ‘flow’ of internodular matrix during step formation. Local plastic deformation in the initiation zone and the corresponding value of critical strain energy release rate, G_Ic, were correlated with the nodular morphology. The size of nodules was found to vary with the curing agent concentration, thus allowing us to establish a fundamental correlation between the nodular morphology and the ultimate mechanical properties of epoxy resins.     

Dicyanate ester–polyetherimide semi‐interpenetrating polymer networks. II. Effects of morphology on the fracture toughness and mechanical properties

A high temperature thermosetting bisphenol‐A dicyanate (BADCy) was modified with polyetherimide (PEI) at various compositions. The effects of the morphology of the blends on the fracture toughness and mechanical properties were investigated. For this purpose, fracture, flexural, and compression tests were carried out. The fracture surfaces of the broken specimens were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The morphology was controlled by changing the curing conditions and PEI content. A good correlation between fracture properties and microstructural features of the mixtures has been observed. The phase‐inverted morphologies showed the highest fracture toughness, which was further increased by increasing the cure temperature. The mechanical properties of the matrix (modulus, yield strength) were not affected by the addition of the thermoplastic. Fracture energy values show similar trends for the different mechanical tests performed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2759–2767, 2001