Papers by Keyword: Compressive Load

Abstract: Carbon fiber composite material with light weight, high strength, corrosion resistance and other characteristics of its impact damage mechanism is different from the traditional metal materials. In this paper, the quasi-static compression of carbon fiber composites was carried out by using a material testing machine to analyze the damage mechanism. The Hopkinson bar technology was used to test the dynamic mechanical properties. The damage mechanism of the carbon fiber composites under dynamic compressive loading was studied. Stress - Strain relationship of composites under Quasi - static and dynamic compressive load. It is found that the main failure mode of out-of-plane direction of carbon fiber composite laminates is brittle shear failure, while the in-plane failure mode shows the properties of brittle materials.

Abstract: The influence of an applied high compressive load on strength of concrete has been studied both theoretically and experimentally in great detail in the past. It was observed that load bearing capacity of concrete decreases under the influence of sustained compressive stress. In this contribution the influence of high sustained compressive stress on capillary absorption and on chloride penetration will be described. It was found that under the influence of moderate sustained compressive load the amount of capillary absorbed water decreases. If the sustained compressive load overcomes 50 % of the material’s strength, the rate of capillary absorption increases. This fact can be explained by reduction of the pore space under moderate compressive stress and formation and time-dependent growth of micro-cracks in the composite structure of concrete. Dissolved chloride is filtered out of the aqueous salt solution and remains accumulated in a surface near layer. In this way a high concentration difference of chloride is built up in a short time. This gradient leads to long lasting diffusion of chloride deeper into the pore space. As the diffusion coefficient of dissolved ions in the pore liquid increases with increasing applied compressive load, service life of structural elements under high compressive load will be reduced significantly when exposed to aggressive environment. This fact has to be taken into consideration if service life of reinforced concrete structures is to be predicted in a realistic way.

Abstract: The Ritz method is used for the buckling analysis of stiffened plates under compressive load. Suggested approximations of displacements allow taking into account the features of system wave formation. The results are compared with data, received by finite element method.

Abstract: The mechanical properties of the sharp end, equator and blunt end of White-duck-eggshell were tested through the compression experiment, and the static load mechanical properties of the eggshell were simulated with finite element analysis method. The results showed that the maximum pressure that the loaded long axis of the eggshell can endure is obviously greater than that of the short axis, and that the maximum pressure that the sharp end can endure is greater than that of the blunt end in the long axis. Furthermore, the same results have been obtained both by finite element analysis (FEA) and experimental study, which can prove the feasibility of the FEA in the analysis of eggshell mechanics properties.

Abstract: The focus of this paper is to study the energy absorption characteristics of aluminium foam filled sections. The energy absorption capability of square mild steel foam filled and empty samples to absorbed mechanical energy have been estimated according to the results from the compressive tests. The tests were performed on the universal testing machine .The experimental results shows that aluminium foam filled sections feature have good energy absorption at various strain rates from 10^-3/s to 10/s.

Abstract: In this paper, to study mechanical behavior of steel box stub column under cyclic uniaxial tensile and compressive load, elasto-plastic analysis of the segment is carried out by using ABAQUS package. In this study, with changing parameters (such as length-width ratio L/B, width-thickness ratio R_R) of the box stub column, the hysteresis curves, skeleton curves, stress distribution and deformation of the ultimate state for the steel box stub-column are investigated. These results show the L/B and R_R have little impact on the ultimate strength and ductility of stub-columns during the tensile stage. However, R_R has obvious impact on the elasto-plastic mechanical behavior and local deformation under compressive load.

Abstract: Concrete failure surface is the most important tool to predict concrete strength under complicated load. Most concrete structures in cold regions are subjected to both external loads and freezing-thawing, while now most researchers focused on the freeze-thaw durability of concrete without external loads. To make up the deficiency, the degradation of compressive strength of concrete under the simultaneous action of external loads and freezing-thawing are experimentally investigated in this research. Finally, a concrete failure criterion is adopted to establish an applicable failure surface in principal stress space for concrete.

Abstract: This paper presents the experimental results of the wood columns externally strengthened with fiber reinforced polymer (FRP) subjected to axial compressive loading. In total, 14 square short wood columns were made, which were reinforced by FRP in two reinforcing arrangements. The main parameters studied in the test were (1) the strengthening materials, i.e. carbon FRP (CFRP), basalt FRP (BFRP) and aramid FRP (AFRP); (2) the reinforcing arrangements, i.e. the full wrapping of FRP and the partial reinforcing arrangement; (3) the layers of FRP sheets applied, i.e. one, two and three. The ultimate strength, load-axial displacements curves, load-strain relationships, and the failure modes of all the columns were presented. The test results show that both types of the reinforcing arrangements could increase the ultimate strength and stiffness of the columns tested greatly. The columns strengthened with two layers of FRP sheets gave higher load carrying capacities when compared to the columns strengthened with one or three layers of FRP sheets. The result confirms that the more layers of FRP sheets, the higher of load carrying capacity; however, the adverse results were shown when three layers of FRP sheets applied. Finally, the result also showed that the full wrapping reinforcing arrangement is more effective than the partial one in enhancing the stiffness.

Abstract: The advantages of polymer materials such as high strength and stiffness to weight ratio, corrosion resistance and manufacturing flexibility have increased the industry demands to utilize them in high performance applications. Designing polymer structures depends on a high understanding of their hyper-elastic behaviour, therefore investigating the mechanical behaviour of polymers is necessary. In this paper, the nonlinear behaviour of epoxy polymer is examined under upsetting test. The main aim of the study is to analyse the effect of strain rate on the mechanical behaviour of epoxy polymer. The cylindrical polymer epoxy specimen, 20mm in length and in diameter, was manufactured. The upsetting tests provided quasi-static compressive loads which were adjusted in the loading rates of 0.1, 1, 50, 100, 200 and 500 mm/min. The loadings were continued until complete fracture was observed. Each loading rate was repeated for at least 3 specimens to ensure a reasonably good statistical sampling. The average data of each test is used to produce the load-displacement graphs of the specimens, from which stress-strain curves are extracted to show the behaviour of epoxy polymer. The results show a 37% increase of yield stresses when the loading rate is increased from 0.1 to 500 mm/min and the yield strains increase by 26%. The stress-strain curves are nonlinear where the slope increases when the loading rate is raised from 0.1 to 100 mm/min but then decreases when the rate is further raised from 100 to 500 mm/min. The maximum load that can be sustained is increased with loading rate. This can be due to the microstructure deformation response of epoxy polymer. This polymer is categorised as large-strain material by showing exhibiting large deformations under different rates of compression loading.

Abstract: In this paper the biomechanical behavior and numerical evaluation results of three C3-C5 porcine cervical models created with different modeling techniques are shown. The objective of this evaluation is to know the differences between the biomechanical effects on a bone graft, which replaces a damaged C4 vertebral body, a titanium alloy (Ti-6A1-4V) cervical plate, used to isolate the C4 damaged vertebra, and the influence on the compressive loads on the complete and instrumented C3-C5 cervical model. The biomechanical integrity of the healthy C3 and C5 vertebral body after the fixation of the cervical plate using titanium alloy screws is considered. Besides, 2-D Computer Tomography classic technique, 3-D Scanner Z-Corp 700 and a CT scanning Philips Brilliance system was used to create the three FEM models. In addition, 3-D Software as Pro-E Wildfire 4.0, ScanIP 3.1, UGS NX-4 and Geomagics R 10.0 was used to create specific numerical model. Main displacements and von Misses stresses between the upper and lower surfaces of the vertebral bodies and the bone graft and the influence of the titanium alloy (Ti-6A1-4V) screws on the vertebral body of C3 and C5 were evaluated. The contribution of this study is to optimize the actual surgical technique once the numerical results on the FEM model have been analyzed. In other words, the numerical disparity between classic CT techniques versus 3-D modern techniques is established.