Papers by Keyword: Compression Property

Abstract: A series of refractory high-entropy alloys VTaTiMoAl_x with x=0,0.2,0.6,1.0 were designed and produced by vacuum arc melting. The effect of added Al elements on the microstructure and mechanical properties of refractory high-entropy alloys were investigated. The X-ray diffraction results showed that all the high-entropy alloys consist of simple BCC solid solution. SEM indicated that the microstructure of VTaTiMoAlx changes from equiaxial dendritic-like structure to typical dendrite structure with the addition of Al element. The composition of different regions in the alloys are obtained by energy dispersive spectroscopy and shows that Ta, Mo elements are enriched in the dendrite areas, and Al, Ti, V are enriched in inter-dendrite areas. The yield strength and compress strain reach maximum (σ0.2=1221MPa, ε=9.91%) at x=0, and decrease with the addition of Al element at room temperature. Vickers hardness of the alloys improves as the Al addition.

Abstract: The elements Mo, Cr and V were added to the W-Ni-Co system high entropy alloys, the effects of these added elements on microstructure and mechanical properties of these alloys were studied. The alloys were produced by vacuum arc melting. The compositions were W_0.5Ni₂Co₂VMo_0.5, W_0.5Ni₂Co₂VCr_0.5 and W_0.5Ni₂Co₂CrMo_0.5 (denoted as Alloy 1, Alloy 2 and Alloy 3) respectively. The theoretical melting temperatures were higher than 2000 K. X-ray diffraction, SEM and energy dispersive spectroscopy (EDS) results indicated that the matrix of the alloys is face-centered cubic (FCC) solid-solution, the alloys showed dendrite crystal structure. Ni, Co elements were enriched in the dendrite areas, the W, Mo were enriched in the inter-dendrite regions ,while V, Cr elements were uniform distribution. The Vickers hardness of these alloys was 376.1 HV, 255.88 HV and 306.8 HV, respectively. The yield strength values (σ_0.2) of Alloy 1, Alloy 2 and Alloy 3 were approximately 1000MPa, 750MPa, 250MPa, respectively. The alloys show good compression plasticity deformation capacity at RT.

Abstract: Several kinds of Glass Fiber Reinforced Polymer (GFRP) bars with different winding materials were manufactured through modifying the production process. Based on the experiments, compression and bending properties were tested. Through the observation of experiment phenomenon and the analysis of test date, the influence and mechanism from different winding materials are discussed. The test results that winding materials affect the compressive strength and bending strength of GFRP bars to a certain extent.

Abstract: The compression properties of C/SiC composite and Inconel X-750 helical springs were investigated from room temperature (RT) to 1000°C in air. The density of C/SiC spring is 1.74 g/cm³, only ~1/5 of X-750 value (8.17 g/cm³) and the spring constants of C/SiC and X-750 springs at RT are 3.47 and 5.61 N/mm, respectively. The spring constants of X-750 spring decreased with increase of temperature. X-750 spring could keep excellent property below 600°C, but its spring constant was only 36.7% of RT value at 800°C and permanent deformation appeared. At 1000°C, it could not restore and was destroyed. The spring constants of C/SiC spring at 400°C and 600°C were appreciably higher than the RT value, and then decreased with temperature elevating. Above 800°C, the spring constant decreased with test progressing because of the oxidation of carbon fibers and SiC matrix. But it has a spring constant of 2.40 N/mm (69.2% of the RT value) at 1000°C and can revert to its original dimensions.

Abstract: In order to studying the failure patterns under impact compression of Hybrid Fiber Reinforced Concrete(HFRC), tests focused on static and dynamic compression properties according to steel fiber reinforced concrete(SFRC) and HFRC are adopted. The equipment of dynamic compression properties test is Ф74mm split Hopkinson pressure bar (SHPB). The static and dynamic compressive strength at four different strain rates of the two materials are obtained, while failure mechanism has been analyzed from specimens’ failure modes in static and dynamic compressive tests, which in turn provides theory basis for the application of HFRC.

Abstract: In this study, by changing Z-pin’s insertion parameters, the X-cor sandwich was prepared with vacuum curing molding process. The effects of Z-pin’s insertion angle, insertion density and diameter on compression, shear and tension properties were studied. The results show that Z-pin’s insertion parameters can significantly affect the mechanical properties of X-cor sandwich. The compression properties of X-cor sandwich are reduced, while shear properties are improved by the increase of Z-pin’s insertion angle. As Z-pin’s insertion angle increases the tension modulus increases while the tension strength firstly increases and secondly decreases. The mechanical properties increase with the increase of Z-pin’s insertion density and diameter. Compared with the foam core sandwich, the mechanical properties of X-cor sandwich are significantly improved in both modulus and strength.

Abstract: Using Al powder as thickening agent and CaCO3 powder as foaming agent, Al foams with above 85% porosity, pore sizes between 1mm and 4mm and relatively uniform pore structure have been fabricated by melt foaming method at different foaming temperatures. Meanwhile, the paper researched the effect of foaming temperature on foaming effect and analyzed the defects in Al foams. At last, compression test were taken in order to investigate the mechanical properties of aluminum foams. The results showed that pore structure, pore distribution and compression properties of Al foams fabricated at 720°C were much better than that fabricated at lower temperature.

Abstract: Three-dimensional non-woven liner is a new kind of material. Six different kinds of fibers with different ratios are used in the paper. Cyclic compression test of finite strain is conducted by Instron 3365. And then regression analysis on compression curves is performed with the SPSS software. Indicators of softness and compression recovery can be determined through correlation and variance analysis. The values of these samples’ indicators are calculated. The raw material’s composition and its influence on compression property are analyzed in order to provide basis for the development of three-dimensional non-woven liner material.

Abstract: The polyurethane foam composite was prepared by alkali lignin and renewable polyurethane foam (PUF). The thermal stability as well as compression property was studied. It was obtained from the TG curve and the DTG curve that the initial decomposition temperatures of polyurethane foam composites with 10% renewable PUF and without renewable PUF were 560.25K and 574.13K,respectively, which showed the renewable PUF affacted the thermal stability of the polyurethane foam composite. The compressive strength (σ10)was from 203kPa to 125 kPa , which were affacted by the dose of the renewable PUF.

Abstract: The cell-structure of highly porous aluminum material prepared by foaming of aluminum alloy melt with titanium hydride was investigated nondestructively with fine-focus X-ray 3D-CT at several interrupt steps during slow compressive deformation. The foamed highly porous aluminum has anisotropic shape of each cell inevitably because of gravity force during solidification of foamed material and mechanical properties especially the dependence on the deformation direction of highly porous aluminum is analyzed well from the size and shape of each void composing the porous material. The statistic anisotropic distribution of these form factors such as three axial lengths and directions at the time of ellipsoidal approximation of each cell was found to be less important to improve the mechanical properties of this type of material.