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关键词： plastic deformation   internal friction   shear strength   triaxial compression   “Brazilian”test   loading diagrams  

摘要： [Objective]The work is devoted to the study of irreversible deformation of artificial samples subjected to a set of standard experiments,with an aim to study their mechanical *** principal idea of the study is related to the preparation of an artificial material with an established constitutive behavior *** existence of such a well-described material provides future opportunities to conduct controllable experiments on various mechanical processes in rock-like material for further development and validation of theoretical models used in rock mechanics.[Methods]A set of artificial samples was prepared for careful assessment through a number of loading *** work was carried out to determine the rheological properties under conditions of triaxial compression tests and uniaxial *** loading tests are completed for 9 samples with varying radial stress levels(0-5 MPa).The samples are loaded up to the yield point with control of radial and volumetric *** experimental results,which contain the obtained interrelationships between axial and radial stresses and strains,are analyzed using the Drucker-Prager yield *** hardening is taken into account through the non-associated plastic flow law with the cap *** modeling of sample loading is performed through the finite difference *** model parameters are adjusted to minimize the discrepancy between numerical modeling results and experimental *** design of a series of experimental studies necessary to determine all the parameters of the model has been studied.[Results]It is shown that the formulated mathematical model allows to reliably reproduce the inelastic behavior of the studied material,and it can be used to solve a set of applied problems in continuum mechanics,the problem of numerical simulation of hydraulic fracture growth in an elastoplastic medium in *** was found that for the entire range of applied lateral loads(0-5

关键词： 约束力   超静定问题   材料力学   解题  

摘要： 问题:试求图1所示超静定梁的两端约束力。设固定端沿梁轴线的约束力可以忽略[1]。解题:超静定问题是材料力学的重点,同时也是材料力学的难点。学生常常不能正确分析超静定次数、不能正确求解力法正则方程、不能正确利用对称性与反对称性。

关键词： 材料力学   周培源力学竞赛   命题思路  

摘要： 对第十四届全国周培源大学生力学竞赛(个人赛)试题的材料力学试题部分进行了概要分析,包括介绍命题原则与思路,说明各个题目的知识考核要点以及解题思路,为组织和参加全国周培源大学生力学竞赛的广大师生提供相关教研和学习交流的参考。

关键词： 碳纤维复合材料   树脂   缺陷   固化   力学性能  

摘要： 树脂浸润时间是复合材料液体成型工艺重要参数。旨在研究树脂浸润时间对碳纤维平纹机织层合复合材料(CFPWLC)性能的影响。通过调控不同浸润时间(2小时、4小时、6小时),制备具有不同树脂孔隙体积分数的CFPWLC样品并分析面外/面内压缩力学性能。结果显示:相比于进料区,浸润时间对出料区影响更显著。从2小时到6小时,材料出料区的质量、面外/面内强度分别增加了4.47%、53.02%、63.58%,破坏形貌由层间破坏转为剪切破坏。此外,采用超景深表面形貌观察试样缺陷,发现缺陷位置主要集中于经纬纱线交织处。这些发现为优化复合材料制备工艺提供了重要参考。

关键词： 碱激发胶凝材料   固废利用   矿渣-粉煤灰   力学性能  

摘要： 碱激发胶凝材料是一种新型的绿色水泥,不仅具备优异的力学性能,还能有效利用固废材料(矿渣、粉煤灰等)。下文通过系列试验研究,探究了不同粉煤灰替代量对碱激发矿渣胶凝材料(又称碱矿渣水泥)净浆和砂浆力学性能(抗压和抗折)的影响,研究表明,当粉煤灰替代量低于50%时,对碱矿渣水泥试件的抗压与抗折强度影响不大;当粉煤灰替代量超过50%时,其抗压抗折强度迅速下降。

关键词： 金属材料   力学性能   精度提升  

摘要： 现代工业中金属材料广泛应用于航空航天、汽车制造等领域,然而现有检测方法受设备、试样、环境及人为因素影响,精度有待提升。文章针对检测设备、试样制备、环境因素及人为操作等因素进行分析,研究其对金属材料力学性能检测精度的影响。研究结果表明,通过优化设备、改进试样制备工艺、控制环境条件、完善人员培训与操作规范,可显著提升检测精度。通过文章研究,为准确评估金属材料性能提供了有效途径,对相关行业发展具有重要意义。

关键词： laser cladding   FeCoNiBSiNb composite layer   tribological property   Si content  

摘要： Aseries of [(Fe_(0.6)Co_(0.2)Ni_(0.2))_(0.75-0.03x)B_(0.2)Si_(0.05+0.03x)]_(96)Nb_(4) amorphous alloy composite coatings were prepared by adjusting the silicon content(x=0,1,2,3,4,5,and 6)and their microstructures and tribological properties were investigated by laser cladding ***,the effect of Si on the glass forming ability(GFA)of the layers was *** show that an appropriate Si content can refine the microstructure of the FeCoNiBSiNb laser cladding layers and improve the mechanical and tribological *** hardness of the coating layer increases monotonically with the Si *** the Si content of 4.8at%(x=0),the coating layer exhibits a relatively low hardness(734.2HV 0.1).Conversely,at the silicon content of 13.44at%(x=3),the coating layer exhibits the highest hardness(1106HV 0.1).The non-crystalline content and tensile strength exhibit an initial increase,followed by a subsequent *** x=2,the coating exhibits its maximum fracture strength(2880 MPa).However,when x>2,the fracture strength of the coating decreases with an increase in ***,with an increase in Si content,the wear volume loss initially decreases and then *** a Si content of 10.56at%(x=2),the coating exhibits the highest non-crystalline content(42%),the highest tensile strength(2880 MPa),and the most favorable dry friction performance.

关键词： 粉煤灰掺量   工程水泥基复合材料   抗压强度   拉伸性能   弯曲性能   开裂性能  

摘要： 为了探究粉煤灰掺量对ECC力学性能的影响规律,通过控制水胶比(0.28)、PVA纤维掺量(1.5%)等参数不变,采用单因素试验方法对粉煤灰掺量60%~80%的ECC材料进行抗压强度、拉伸性能及弯曲性能测试。结果表明,随着粉煤灰掺量增加,ECC材料的弹性模量、开裂强度、断裂韧性、抗压强度、抗拉强度及弯曲强度均降低,其中80%掺量时抗压强度仅为60%掺量的48.47%;而材料的拉伸应变和弯曲应变则随掺量增加而增加,表现出良好的延性特征。

关键词： 玄武岩纤维   聚丙烯   力学性能测试   增强聚丙烯复合材料   硅烷偶联剂改性   界面结合性能  

摘要： 采用酸碱刻蚀法和硅烷偶联剂法对玄武岩纤维(BF)进行改性,利用熔融共混法制得改性玄武岩纤维-聚丙烯(MBF-PP)复合材料,分别研究不同浓度的HCl(1、2、3 mol/L)和NaOH(1、2、3 mol/L)联合不同种类硅烷偶联剂(KH550、KH560、KH570)的MBF对其复合材料力学性能的影响。结果表明:使用1 mol/L HCl刻蚀改性的BF制备的MBF-PP复合材料拉伸强度为19.5619 MPa,相比纯PP提高6.8%;使用2 mol/L NaOH刻蚀改性的BF制备的MBF-PP复合材料拉伸强度为20.0667 MPa,相比纯PP提高9.5%;使用NaOH改性的抗拉强度均高于HCl,但对浓度要求更高;使用HCl和KH550联合改性的MBF-PP复合材料力学性能比单独改性的MBF-PP复合材料低;使用KH570改性的MBF-PP复合材料力学性能最高,但同时塑性也较高。

关键词： 火灾   SEM   力学性能   温度场  

摘要： 某钢筋混凝土结构厂房,因接线端子表面氧化等原因造成接触电阻增大导致其发热,致使周边塑料发生燃烧引发火灾,火势持续约5h,消防人员采用浇水冷却进行灭火。受火灾影响,厂房结构构件发生不同程度损伤,为明确结构构件现有的实际损伤程度,本文依据现场调查结果,将厂房划分为受火灾影响程度一般区域、受火灾影响程度严重区域,并采用SEM(扫描电子显微镜)对其微观物相特征进行观察,依据T/CECS 252-2019《火灾后工程结构鉴定标准》对三面受火梁或四面受火柱的截面温度场曲线进行分析,推断火灾后钢筋混凝土的力学性能变化规律,得出钢筋屈服强度和混凝土与钢筋的粘结强度有较大损伤,而混凝土内部强度损伤不甚明显的结论。