Papers by Keyword: Elastic Modulus

Abstract: Although the machine-made sand was widely used for concrete in recent years in China, it was short of studies on the relations among the basic mechanical properties of fly-ash concrete with machine-made sand (MSFAC). However, these relations such as the compressive strength, the tensile strength and the elastic modulus with the cubic compressive strength (i.e. strength grade) are the basis of design for concrete structures. This paper summarizes the test data from the published references, and discusses the relations among these properties by statistical analyses compared with those of ordinary concrete. The results show that only the tensile strength of MSFAC can be safely forecasted by the same formula of ordinary concrete specified in current Chinese design code. When the strength grade is higher than C45, the axial compressive strength of MSFAC is largely forecasted by the formula of ordinary concrete. The elastic modulus of MSFAC is larger than that of ordinary concrete, which should be prospect by the formula in this paper. This work gives out some cautions for the proper use of the MSFAC in concrete structures.

Abstract: The mechanical behaviors and durability of concrete containing steel slag powder (SSP), silica fume (SF) and fly ash (FA) were presented in this study. The fresh concrete properties, compressive strength, split tensile strength, elastic modulus, stress-stain curve, chloride permeability as well as carbonation of concretes mixed with different SSP contents or concretes containing compound mineral admixture were tested. The experimental results reveal that the mechanical behaviors and durability of concrete with 10% SSP replacing cement are both improved than that of the reference concrete. Mechanical behaviors and durability of concrete with 20% SSP replacing cement are similar to the reference concrete. Concrete with compound mineral admixture of SSP and SF obtain the highest enhancement in both strength and chloride resistance.

Abstract: Different surface forms will have a huge impact on bond of GFRP rebar and concrete, and the ribs depth is the key factor that affects the bond with concrete, therefore, the surface forms and rib depth should be taken into account when GFRP bars are used as the structural reinforcement material. Based on two kinds of rib spacing and rib depth of GFRP reinforcement on tensile performance test, this article studies the different influence of ribs depth on the tensile properties and mechanism. Experimental results show that rib depth has distinctive impact for the GFRP tendons ultimate tensile strength, elastic modulus and ultimate elongation.

Abstract: Warp knitted fabrics possess a number of changes in the structures, so they do have great advantages on the property design of composites. The three kinds of weft insertion warp knitted fabrics are knitted on a Raschel latch needle warp knitting machine with glass continuous-filament yarns. The warp knitted fabric/ unsaturated polyester resin composite laminates are produced by manual molding technology. The tensile properties of composites in the course, wale and diagonal directions are tested on the universal material testing machine. The results show that the tensile stress/strain curves of the composites were nonlinear. The tensile properties of the composites possess obvious anisotropic characteristics. The tensile strengths and elastic modulus of the warp knitting composites depend on the needle space number of inlaid yarn, fabric density and structure.

Abstract: Mechanical properties of porous silicon nitride prepared by two different processing routes have been studied. Depth sensing methods was used to measure the hardness and elastic modulus of experimental materials. The results were compared with the hardness and elastic modulus of trabecular bone in order to find out porous ceramics with properties close to that of trabecular bone. Material prepared by infiltration of polyurethane sponge exhibited properties close to the properties of bone and it is the potential material for further investigation in the bioapplication field.

Abstract: Local mechanical properties of high Cr-alloyed sintered and cast steels with the same chemical composition were investigated using instrumented indentation method. Standard loading/unloading mode was applied, the measurements were done in load range 1 – 500 mN. Load size effect was observed and its parameters were evaluated. Indentation hardness and elastic modulus were found slightly higher for the sintered material. Differences in indentation parameters were explained based on microstructure of materials.

Abstract: When the depth-sensing (nano)indentation is applied to sintered samples, measured properties, which are expected to represent the material of an individual grain, seem to depend on the overall porosity of the macroscopic sample. To understand such a result, it is assumed that while the nanoindenter penetrates into the surface grain and probes the properties of its material, the grain itself serves as another, larger indenter indenting the rest of sample and probing the properties that represent the bulk of material rather than individual grains. Load vs. displacement curve reflects the synergetic response of these two “indenters” and so it contains information about the sample’s mechanical properties at both microscopic and macroscopic scales. Obtained theoretical results agree qualitatively with the experimental data (the dependence of the indentation modulus on the porosity of sample; the indentation size effect).

Abstract: The use of nanoindentation techniques enhances the capabilities of qualitative analysis of elasto-plastic characteristics, especially, estimating mechanical properties of relatively small specimens in their surface layers. The results are in agreement with macromethods, which gather the information over the higher volume of the material. It was confirmed, that hardening of double phase Ti-6Al-4V alloy by quenching from beta temperatures (above beta-transus), reduces the elastic modulus by about 8 % due to increased ratio of low-modulus beta phase from 8 to 34 %.

Abstract: Molecular dynamics (MD) simulations were performed on molecular models of cellulose represented by two crystalline samples and amorphous samples. Simulated elastic properties and structures of each cellulose model were studied by MD simulations with the reactive force field and compared against experimental data for corresponding sample. The simulation boxes in stretch provide the materials elasticity. When there is a strain, the energy increases and internal stresses were built up within the supercell. The elastic moduli of amorphous and crystalline cellulose were comparable to the literature value. The calculated results had negligible difference with the experimentally measured parameters that indicated that the initial structures were stable using the ReaxFF.

Abstract: t is presented a method for determining the mechanical characteristics based on the vibration response of the CMT (Cold Metal Transfer) joints from thin sheets of stainless steel joined with CuSi3 filler wire. The experimental results obtained by vibration testing will be compared with the theoretical results, and with those obtained by classical methods from stress-strain diagram. Technical details are given also for obtaining these joints (parameters, equipment specifications) indicating also their applicability.