共查询到20条相似文献，搜索用时 31 毫秒
1.
Rocks are heterogeneous from the point of microstructure which is of significance to their dynamic failure behavior. Both the compressive and tensile strength of rock-like materials is regarded different from the static strength. The present study adopts smoothed particle hydrodynamics (SPH) which is a virtual particle based meshfree method to investigate strain rate effect for heterogeneous brittle materials. The SPH method is capable of simulating rock fracture, free of the mesh constraint of the traditional FEM and FDM models. A pressure dependent J-H constitutive model involving heterogeneity is employed in the numerical modeling. The results show the compressive strength increases with the increase of strain rate as well as the tensile strength, which is important to the engineering design. 相似文献
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毛文宫 《福建工程学院学报》2022,(6):527-531
基于机械力化学作用原理,采用高速球磨法提高花岗岩石粉的胶凝活性。研究活化石粉掺量对胶砂抗压强度、折压比和干燥收缩性能的影响规律,结合XRD、SEM、MIP 等微观试验,揭示活化石粉的作用机理。试验结果表明:花岗岩石粉活性指数可从0.55 提升至0.73,活化石粉替代20%~30%水泥用量的胶砂强度28 d 抗压强度达30 MPa 左右,折压比提高约30%,干燥收缩降低约60%。 相似文献
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探讨将具有良好弹性和柔韧性的废旧轮胎橡胶作为粗、细骨料,掺入混凝土进行材料改性、以及利用硅灰进行材料性能提升的可行性。试验研究结果表明:轮胎橡胶颗粒替代砂石骨料掺入混凝土后,其抗压强度、抗折强度以及弹性模量均随着轮胎橡胶骨料含量的增加而降低。粗橡胶颗粒对于强度的削弱要明显大于细橡胶粉。但是,当粗橡胶颗粒掺量不超过10%,细橡胶粉掺量不超过25%时,改性后混凝土力学性能没有太大的降低。而且在此掺量下,掺入少量的硅灰,就可以大大提升橡胶集料混凝土的力学性能,使其强度接近或超过普通混凝土。与普通混凝土相比,橡胶混凝土破坏过程柔和缓慢,特别是细橡胶集料混凝土具有更好的韧性。 相似文献
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In this study, the efficiency of bitumen and asphalt mixtures modified with crumb rubber （CR） and recycled glass powder （RGP） is evaluated. From an environmental point of view, the application of RGP in asphalt mixtures is considered beneficial since it prevents accumulation of waste glass in the natural environment. Rheological and mechanical properties of modified bitumen samples were investigated by laboratory methods such as bitumen conventional tests and dynamic shear rheometer （DSR）, and also by asphalt mixture performance tests including Marshall stability, indirect tensile strength （ITS）, compressive strength, and indirect tensile stiffness modulus. The results showed that the application of RGP in place of CR has no negative impact on the efficiency of bitumen and asphalt mixtures and even improves their engineering properties except for the toughness index （TI）. Moreover, a modification with 5% CR and 5% RGP in asphalt mixtures results in the best overall performance. 相似文献
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The development of biodegrad able bone cement systemhas received considerable attention over the past fewyears .One of the most important and attractive families is biode-gradable polyesters .They can be used as biomaterial scaf-fold to provide mechanical… 相似文献
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李惠霞谢祥冰林上顺 《福建工程学院学报》2020,(1):6-11
为了推动大粒径沥青碎石柔性基层在路面结构中的应用,通过室内试验的方法,对掺入橡胶粉和玻璃纤维的大粒径沥青碎石进行了抗压强度、抗拉强度、抗弯拉强度和回弹模量试验及高温稳定性能、低温性能和水稳定性实验,探讨了外掺剂种类和含量对大粒径沥青碎石力学性能和路用性能的影响。结果表明:加入外掺剂后大粒径沥青碎石ATB-30的力学性能和路用性能能完全满足规范要求,尤其是玻璃纤维对大粒径沥青碎石性能的改良效果会更加明显,在外掺剂橡胶粉和玻璃纤维的作用下,适当减少沥青用量,既能保持ATB-30力学特征和路用性能不会减弱,又降低了大粒径沥青碎石工程造价。 相似文献
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以超细钢铁渣粉(以下简称“超细钢渣”) 为主要掺合料制备胶凝材料,通过XRF、粒径分析、XRD分析和力学性能测试,探究超细钢渣对水泥基材料的力学性能影响。结果表明:通过机械研磨制备出的超细钢渣,其矿相成分硅酸三钙、硅酸二钙和莫来石特征峰强度最强,复掺的超细钢渣活性指数也满足国家标准。随着超细钢渣掺量增加,3 d 抗压和抗折强度均出现逐渐降低的趋势,但在外掺m (超细钢渣) ∶ m (超细矿渣)= 2:3、w复合粉=30%时,其28 d 抗压和抗折强度达到峰值,分别为8.9、53.8 MPa。超细钢渣在不同龄期水化反应程度不同,早期水化反应较低,强度较差;后期水化程度较高,且优于同标准水泥。 相似文献
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蔡军 《商洛师范专科学校学报》2014,(2):28-30
为了研究聚丙烯纤维自密实混凝土的工作性能和力学性能。采用坍落扩展度试验和V型漏斗试验对聚丙烯纤维自密实混凝土的工作性能进行了检测,并对聚丙烯纤维自密实混凝土立方体试件进行了抗压强度和劈裂抗拉强度试验。用JSCE—SF4方法对聚丙烯纤维自密实混凝土的抗弯韧性进行评定,比较分析了不同掺量的聚丙烯纤维对自密实混凝土工作性能和力学性能的影响。研究结果表明,随着纤维掺量的增加,聚丙烯纤维自密实混凝土的抗压强度略有降低,劈裂抗拉强度和抗弯韧性均明显提高,聚丙烯纤维能够有效提高自密实混凝土的劈裂抗拉强度和抗弯韧性。 相似文献
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丁进炜 《福建工程学院学报》2019,(1):13-16
在再生粗骨料取代率为70%的基础上,研究经碳化强化处理的再生细骨料对再生混凝土基本力学性能的影响规律。并与未碳化再生细骨料的情况进行对比,再生细骨料的取代率为0、20%、30%、40%。实验结果表明:再生混凝土抗压强度随再生细骨料取代率提高而减小,碳化再生细骨料可提高再生混凝土抗压强度。 相似文献
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再生混凝土力学性能的研究 总被引：1，自引：0，他引：1
对再生混凝土力学性能的研究进行了综述，主要包括再生混凝土力学性能的抗压强度、弹性模量、干缩与徐变。研究表明，和普通混凝土相比，再生混凝土力学性能的抗压强度低，弹性模量小，干缩与徐变较大。最后提出了再生混凝土力学性能需要进一步研究的问题。 相似文献
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采用一种新型的离心喷射沉积(CSD)成形技术制备了Ti—48A1—2Mn—2Nb金属间化合物，较系统地研究了该合金的微观组织结构以及室温拉伸、压缩和断裂韧度等力学性能，探讨和研究了该合金制备过程中形成的孔隙、特殊层片状组织及对材料性能的影响规律。图像分析系统定量测试结果表明，CSD制备的金属间化合物的孔隙率在2％左右，热等静压(HIP)有效地消除了合金在喷射成形制备中产生的孔隙，致密度达99.6—99．9％。性能研究结果表明，CSD制备的Ti—48A1—2Mn—2Nb合金具有良好的室温拉伸、压缩和断裂韧度等性能，尤其是压缩性能和断裂韧度值，显示了很好的应用前景。 相似文献
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分析了深冲合金化热镀锌钢DX53D＋ZF的镀层组织结构和微观成分,测试了试验钢的拉伸性能、成型性能和抗粉化性能特性。分析结果表明,产品具有良好的塑性应变性能,镀层厚度分布均匀;结构细小致密;镀层铁含量平均为10％,梯度变化平缓。 相似文献
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通过改变碳纤维在混凝土中的掺量,探讨碳纤维对混凝土基本力学性能的影响。实验结果表明：碳纤维对混凝土抗压强度基本没有影响,但对混凝土劈拉强度的影响较显著。当碳纤维掺量为0.08%时,劈拉强度可较素混凝土提高43.3%。同时碳纤维还可明显改善混凝土试件的破坏形态,使试件裂而不碎。 相似文献
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Ultra high toughness cementitious composite (UHTCC) usually shows strain hardening and multiple cracking under static tension loads. In practice, structures could be exposed to high strain rates during an earthquake. Whether UHTCC can maintain its unique properties and provide high structural performance under seismic loading rates largely determines whether it can successfully fulfil its intended function. To determine the rate dependence of UHTCC, uniaxial tensile tests with strain rates ranging from 4×10?6 s?1 to 1×10?1 s?1 were conducted with thin plates. The experimental results showed that UHTCC had significant strain hardening and excellent multiple cracking properties under all the rates tested. The ultimate tensile strain lay in the range of 3.7% to 4.1% and was almost immune to the change in strain rates. The rate of 1×10?3 s?1 seemed to be a threshold for dynamic increase effects of the first crack tensile strength, elastic modulus, ultimate tensile strength, and energy absorption capability. When the strain rate was higher than the threshold, the dynamic increase effects became more pronounced. The energy absorption capability was much higher than that of concrete, and the average ultimate crack widths were controlled below 0.1 mm under all rates. Several fitting formulas were obtained based on the experimental results. 相似文献
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为了模拟井下压裂作用下胶凝酸和清洁酸作用时的碳酸盐岩破裂机制,了解两种酸液体系作用后的强度劣化效应,进行了拟三轴岩石力学试验以及3-D扫描。试验结果表明:与胶凝酸反应后,碳酸盐岩弹性模量、泊松比和抗压强度均呈降低趋势,其中泊松比降低幅度明显,酸蚀90 min时,降幅达到18.15%;与清洁酸反应后,碳酸盐岩弹性模量、抗压强度在酸蚀初始阶段小幅提高,当酸蚀时间达到90 min后,两者降幅分别为21.04%及23.55%,泊松比降幅为4.36%,岩石力学性质劣化效应明显,脆性指数升高12.09%;与胶凝酸反应90 min后,碳酸盐岩的脆性指数提高58.56%,破裂压力呈下降趋势;与清洁酸反应后,裂缝壁面粗糙程度明显降低,裂缝导流能力呈降低趋势。酸压后的力学性质劣化特征可为酸化压裂设计及参数优化提供基础数据。 相似文献
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The joining of aluminum alloy sheets with thickness less than 2.0 mm is difficult via conventional frictionstir welding owing to the defects in the joint, such as root flaw, keyhole and lazy S. In the present research, a newlydesigned pinless tool with involute grooves on its shoulder surface was applied to weld 1.5 mm thick AA2024-T3. Theeffects of the rotating speed and welding speed on the microstructure and mechanical properties of the joints were analyzed.The experimental results showed that the root flaw and keyhole were successfully eliminated. The lazy S wasalso eliminated under the optimized welding parameters. The maximum tensile strength of the joints was 326 MPa,which is about 74.1% that of the base material. Moreover, all the tensile samples fractured from the retreating side.Two fracture modes were observed during the tensile tests, which are related with the lazy S. 相似文献
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通过制备4种不同锰镍比的TWIP合金铸铁,研究了锰镍比对Fe-Mn-Ni系TWIP合金铸铁组织和力学性能的影响。试验结果表明:随着锰镍比从3∶2、2∶1、3∶1和4∶1逐渐增加,铸铁铸态组织中的碳化物含量增加。在1 050 ℃保温10 h后进行水淬,就能使碳化物分解,获得单相奥氏体基体组织。经过热处理后,锰镍比为3∶2的TWIP合金铸铁力学性能最佳,其抗拉强度为885 MPa,伸长率为29.7%。 相似文献
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Numerical Derivation of Strain Rate Effects on Material Properties of Masonry with Solid Clay Bricks
In this paper, numerical method is used to study the strain rate effect on masonry materials. A typical unit of masonry is selected to serve as a representative volume element (RVE). Numerical model of RVE is established with detailed distinctive modeling of brick and mortar with their respective dynamic material properties obtained from laboratory tests. The behavior of brick and mortar are characterized by a dynamic damage model that accounts for rate-sensitive and pressuredependent properties of masonry materials. Dynamic loads of different loading rates are applied to RVE. The equivalent homogenized uniaxial compressive strength, threshold strain and elastic modulus in three directions of the masonry are derived from the simulated responses of the RVE. The strain rate effect on the masonry material with clay brick and mortar, such as the dynamic increase factor (DIF) of the ultimate strength and elastic modulus as a function of strain rate are derived from the numerical results. 相似文献
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本试验在对A、B、C、D、E、G1等6种试剂的助磨作用试验的基础上,着重研究了双组分AGl、BG1、DGl、EGl等复合助磨剂对水泥的助磨效果及主要性能的影响．试验结果表明：双组分AGl、BG1、DGl的助磨效果较好,使水泥的粉磨细度提高了63％—69％,其中AGl使3d、28d抗压强度分别提高25％、12％,特别是用量为0．01％的AGlIo,不仅使细度提高67．0％,而且使28d抗压强度提高12．9％,具有明显的增产节能降耗,提高产品质量的作用。 相似文献