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11.
Alberto Carpinteri Bernardino Chiaia Simone Puzzi 《Engineering Fracture Mechanics》2007,74(17):2892-2896
Aim of this letter to the Editor is at replying to the criticisms raised by Ba?ant and Yavari [Ba?ant ZP, Yavari A. Is the cause of size effect on structural strength fractal or energetic - statistical? Engng Fract Mech 2005;72:1-31] against the fractal approach to the size-scale effects on the mechanical properties of materials and the concept of the Multi-Fractal Scaling Law presented by Carpinteri [Carpinteri A. Scaling laws and renormalization groups for strength and toughness of disordered materials. Int J Solids Struct 1994;31:291-302]. These criticisms will be analysed thoroughly, showing how they also contain some mistakes and misunderstandings. The presented elucidations should redirect the discussion to a more correct scientific debate. 相似文献
12.
针对梅山自产焦炭,利用梅山焦炭反应性试验设备,通过改变焦炭块数、CO2流量和温度等控制参数,讨论了这些参数对焦炭反应性和反应后强度检测值的影响,以及保证测定可靠性应采取的控制措施。 相似文献
13.
14.
The primary aim of this paper is to present results describing in detail the behaviour of ±45° E-glass/MY750 (GRP) tubes, of various wall thicknesses, subjected to equal biaxial tension–compression loading, generated under combined internal pressure and axial compression. The role played by the non-linear lamina shear has also been assessed by comparing various shear stress–strain curves for embedded laminae (extracted from tests on ±45° tubes subjected to circumferential: axial stress ratios SR=1:0, 1:−1 and 2.3:−1) with that of an ‘isolated’ lamina (measured from torsion of 90° tubes). Extracted shear failure strains, for embedded laminae, were more than four fold larger than those measured at ultimate failure for an ‘isolated’ lamina. Soft characteristics were observed in the embedded lamina and these were believed to be due to interaction between early matrix damage initiation (and propagation) and shear. Factors affecting the behaviour of the tubes, such as bulging, scissoring, thermal stresses and stress variation through the thickness are discussed. 相似文献
15.
There is considerable interest in producing fibres that mimic the impressive tensile properties of spider drag line silk. It must, however, be recognised that these properties have been assessed largely on the basis of their average values; there can be significant variability about these averages. The natural variability can also serve as a useful indicator of the range of values over which particular properties of biomimetic silk may be tailored. Here we quantify several tensile properties of drag line from Argiope trifasciata spiders. We distinguish between two groups of properties on the basis of their statistical coefficient of variation. There is significantly greater scope for tailoring the viscoplastic hardening aspects of drag line, compared to the variability of the initial elastic response or the yield strength. We also consider whether elastic modulus, yield strength and viscoplastic hardening can be controlled independently of one another. 相似文献
16.
本文介绍了VAc/BA/MMA三元共聚的两种方法,并通过实验证实:聚合方法对三元共聚物的粘接强度有明显的影响。 相似文献
17.
Material removal and surface damage of Ti3SiC2 ceramic during electrical discharge machining (EDM) were investigated. Melting and decomposition were found to be the main material removal mechanisms during the machining process. Material removal rate was enhanced acceleratively with increasing discharge current, ie, working voltage, ui, but increased deceleratively with pulse duration, te. Microcracks in the surface and loose grains in the subsurface resulted from thermal shock were confirmed, and the surface damage in Ti3SiC2 ceramic led to a degradation of both strength and reliability. 相似文献
18.
Strength reduction factors (SRFs) continue to play a key role in obtaining design forces from elastic design spectra (via
response modification factors) in ductility-based earthquake-resistant design. Despite several years of sustained research
efforts, it has not been conclusively shown how SRF for a given singledegree-of-freedom structural system depends on various
source and site parameters. A parametric study is carried out here for the explicit dependence of SRF spectrum (describing
variation of SRF with system period for a given ductility demand) on strong motion duration, earthquake magnitude, geological
site conditions, and epicentral distance in case of (non-degrading) elasto-plastic oscillators. For this, scaled response
spectra are considered for different combinations of earthquake magnitude, site conditions and epicentral distance, and SRF
spectra are generated from 1274 accelerograms recorded in western USA after making those compatible with each of these spectra.
It is shown that there is no clear and significant dependence of SRF spectrum on strong motion duration. Further, the parametric
dependence on earthquake magnitude, site conditions, and epicentral distance broadly conforms to the trends reported by earlier
investigations. In particular, this study confirms that the dependence of SRF spectra on earthquake magnitude should not be
ignored.
This paper has been contributed in honour of Professor R N Iyengar, Indian Institute of Science, on the occasion of his formal
retirement. 相似文献
19.
In this study, analytical modeling of the tensile strength of hot-mix asphalt (HMA) mixtures at low temperatures was developed. To do this, HMA mixtures were treated as a two-phase composite material with aggregates (coarse and fine) dispersed in an asphalt mastic matrix. A two-phase composite model, which was similar to Papanicolaou and Bakos's [J. Reinforced Plast. Compos. 11 (1992) 104] model with a particle embedded in an infinite matrix, was proposed. Unlike Papanicolaou and Bakos's model, an axial stress was introduced to the fiber end to consider the load transferred from the asphalt mastic the aggregate. Efforts were also made to consider the effect of aggregate gradation, asphalt mastic degradation, and interfacial damage between the aggregates and asphalt mastic matrix on the tensile strength of the HMA mixtures. Experimental investigations were conducted to validate the developed theoretical relations. A reasonable agreement was found between the predicted tensile strength and the experimental results at low temperatures. Parameters affecting the tensile strength of asphalt mixtures were discussed based on the calculated results. 相似文献
20.
使用有限元程序SAP5对某新型导弹发射筒内的适配器的强度进行了计算。通过结果分析,找出了适配器危险应力点的分布规律,它对结构选型设计具有指导意义。 相似文献