Papers by Keyword: Strength Model

Abstract: In the fields of explosive forming, aerospace industry, military industry etc. metallic materials will withstand a high strain rate in the process of deformation. It is very instructive to put forward an accurate strength model which can be used to describe the process of deformation reasonably. In this paper, several strength models are introduced which are mainly based on the macroscopic mechanical behavior of materials and the mechanisms of deformation of material, and their sphere of application, shortcomings and advantages were introduced and reviewed.

Abstract: Several numbers of strength models of FRP-confined circular concrete columns have been published by several researchers. In this study, strength models were proposed based on experimental data. Nine existing FRP-confined strength models of column confinement were reviewed in this study and two forms of strength models of FRP-confined circular concrete columns were proposed. The models were proposed based on different number of experimental data collected from literature. Based on the number of experimental data, i.e. 64-, 106-, 156- and 192-, the strength models were developed. The performance of the existing and the proposed strength models were evaluated and compared. The evaluation results showed that the strength models proposed based on 192-data had the best performance among other models proposed with smaller number of data. It was also shown that the proposed strength models had better performance than the existing strength models.

Abstract: This article discussed the applicability of the curing agent, the growth and change of the peat soil curing unconfined compressive strength and under the different variables (such as cement, curing agent formula, construction waste, age). We get the strength increase model by analyzing the results of peat soil solidification formula experiment. Regress equation about the cement dosage, curing agent, content of construction waste residue, age and principal component values was built by using the regression analysis.

Abstract: This paper is principally performed to survey end-plate connection are described in the next part based on ideal limit states. The determination of end-plate based on the full plastic strength of the steel beam in accordance with 2001 AISC-LRFD manual and AISC/ANSI 358-05 Specifications. The bolted connections considered herein were performed to include the end-plate component of moment connections. This study is intended to investigate economic design for end-plate connections. In addition, the proposed end-plate model is evaluated by comparing the required factored bolt strength. The end-plates using 8 high strength bolts with wider gages demonstrated this design. The equations belonging to the step-by-step design procedure are described based on complete proving of design. Finally, new design methodology is applied to end-plate connections suggested in this study.

Abstract: This paper develops a new advanced strength model for circular columns retrofitted with fiber reinforced polymer (FRP) based on a newly collected test database which is so far the most updated and comprehensive one and has contained more than 800 axial compression test results of FRP confined circular concrete columns. This paper first reviews some existing design-oriented strength models and then provides an in-depth comparison between experimental test results and models predictions. The comparison results indicated that more or less deficiency exists when these models were extended to predict the confined strengths of a much larger amount of columns than that when they were derived, directly resulting in deteriorations of the prediction accuracy. These conclusions exactly reflect the necessity and significance of developing a new advanced confinement strength model in the paper.

Abstract: According to the axial compressive experiment of concrete cylindrical and quadrate specimens confined by Basalt fibers, the stress-strain curves, bearing capacity and peak strain were obtained. 12 quadrate and 12 cylindrical column specimens were prepared and wrapped with 2 to 4 layers of BFRP fibers. The results show that: (1) comparing with unconfined specimens, the compressive strength and peak strain of the specimens confined with Basalt fibers are improved significantly, not only cylindrical but also quadrate; (2) the compressive strength increases with the number of BFRP layers; with equal number of confinement layers, the compressive strength and peak strain of cylindrical specimens is higher than that of quadrate; (3) the wrapped fiber of quadrate specimens are more likely to rupture at the corners of specimen. Meanwhile, the compressive strength models of specimen confined by Basalt fibers were proposed, the theoretical values are in good agreement with the test data.

Abstract: Foam concrete aggregates and inclusions have greater strength, but the pore almost has no compression resistance; hydrated cements and pores are the weak links in the pressure cross-section of the foam concrete. As for unit volume of foam concrete, cement accounts for a large space and the pore occupies less, so the block intensity will be larger. Considering mechanical properties of the aggregates and hydrous cements are different, the volume ratio of hydrous cements to the sum of cements and pores is used to build the strength model of foam concrete, which can be simple and feasible. It can response the foam concrete strength characteristics more accurately.

Abstract: This manuscript makes experiments on the relation between each index and fly-ash concrete strength, such as W/B, Sa, S/A and so on. At the same time we applicate artificial neural networks into HPFC The main research is on the relationship between component material and performance of the high-performance fly ash concrete, and also on the fly ash high-performance concrete quality control system and method, which promotes fly ash in foundation and basement construction engineering application. This text introduces the treatment technology of the non-linear artificial neural network, utilizing mixing ratio of existing concrete (import) and data as the performance index (output) to train the network, setting up concrete to non-linear import--Output mode relation, constructing concrete performance model, promoting prediction precision of concrete performance further.

Abstract: The present work focuses on the failure mechanisms that occur in melt-growth composite ceramics mainly composed of fiber eutectics with random orientation. First, the stress field of the melt-growth composite ceramics under a tensile stress was obtained. It can be visualized that tensile force is transmitted between oxide fiber eutectics by means of shear stress that develop along the interfaces of oxide fiber eutectics. Consider fiber eutectics having lengths smaller than the critical length. During the composite ceramics fracture, fiber eutectics do not fracture. The average stress of a fiber eutectic can be determined by the shear stress. Then, the probability of ending fiber eutectics and bridging fiber eutectics can be gotten by defining a critical ditrict βl. Finally, consider random orientation and length of the fiber eutectics. Composite ceramics failure by slip incompatibility. The strength model of the melt-growth composite ceramics is built. It is accordance with experiments.

Abstract: The SPH (Smoothed Particle Hydrodynamics) solver of the AUTODYN-3D was utilized to demonstrate a remarkable numerical simulation of shaped charges, specifically the process of jet formation and target penetration. A shaped charge consists of an explosive, a case and a conical liner. The Euler solver has been generally utilized for the simulation of the liner collapse process. Though the axi-symmetric modeling of the liner usually is selected, the actual jet formation process is never so idealistic. When we choose options consistent with live fire experiments, the SPH solver produces a more accurate solution over the Euler approach. The SPH method is capable of dealing with problems, including the free surface, deformable boundaries, moving interface and extremely large deformation. Calculated hypervelocity particles using the SPH method precisely represented the actual observed jet formation profiles of shaped charge characteristics. Accurate representations of the jet velocities, a velocity gradient with the tip traveling much faster than the trail and phase changes of the liner material were demonstrated. Using the calculated jet particles from the SPH method, the penetration process was simulated. The calculation was very time-consuming and the results did not conform to the traditional theories of the penetration. We have been investigating this discrepancy.