Papers by Keyword: Strength Prediction

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Authors: Jin He Gao, Shou Long Zhang, Yan Bin Huang
Abstract: This article studied the drilling loading method for the tensile strength of irregular small-stone, designed the measuring devices, and addressed the measurement problems of irregular small-stone tensile strength. Based on static equilibrium theory, it analyzed the distribution rule of tensile stress in dangerous section, and established the mechanics model of drilling loading method. In considering the impact rules of characteristic destruction size and round-hole size on the hole-edge stress concentration, on this basis it established the theoretical formulas of measuring the tensile strength of brittle materials. It practically measured the failure load of small drilling bluestone, introduced the failure load into the theoretical measurement formula of brittle material tensile strength, and then obtained the tensile strength of stones, while it measured the tensile strength of non-porous strip specimen. The tensile strength of irregular stones measured by the drilling loading method is basically consistent with the tensile strength obtained from the tensile test of non-porous strip specimen, and therefore the drilling loading method is able to reasonably measure the tensile strength of small stones.
Authors: Xiao Cong He
Abstract: This study deals with an application of the method of the coefficient of variation in strength prediction of the self-piercing riveted joints. Defined as the ratio of the standard deviation to the mean, the coefficient of variation may be used in both the reliability-based design of self-piercing riveted joints and in the evaluation of existing products. In this study, the concept and definition of the coefficient of variation are stated. The procedure of the use of coefficient of variation for approximate calculations of strength of the self-piercing riveted joints is presented and compared with the classical Taylor expansion method. This is illustrated with a numerical example.
Authors: Jin Chen, Ming Liu, Jie Min Liu
Abstract: Drilling-Hole-Loading method is applied to predicting and measuring the tensile strength of irregular small-size stones. According to this method, a circular-hole must be drilled at the center of the irregular small-size stone. The mechanical model of the stone with a circular-hole and subjected to a pair of equivalent collinear pull forces is set up. The normal stress strain distributions on the critical section are anlyzed. Theoretical stress concentrated factor equation related to the hole diameter is calculated. Based on the static equilibrium theory, the theoretical formula of predicting the tensile strength of irregular small-size stones is established. Based on the theoretical formula, the test device for measurement of the tensile strength of the stone was designed. The tensile strength of a kind of bluestone was measured. The results show that the tensile strength predicted by Drilling-Hole-Loading method is a little lower than that of the standard specimen of stone without hole. Drilling-Hole-Loading method can be used to predict the tensile strength of brittle material and irregular small-size stones.
Authors: Wei Jun Yang, Peng Wang
Abstract: Early age strength of ceramisite concrete gains quickly in strength,the 7d strength can be over 80% of the 28d strength.The thesis researched on relationship between age and strength with a great lot of experiments,and predicted the 28d strength by early age strength,that satisfied the project need.
Authors: Jie Min Liu, Yuan Hong
Abstract: A fine analysis model for joints in axial shear is given on the base of observation of experiment. Failure of the pin connecting adherends is due to combined deformation of pressure-shear. Both critical region of the pin and the stress state in critical rejoin are evaluated. Ultimate load Fu of the joint in axial shear is evaluated with strength criteria. The following conclusions are obtained. (1) Fu is related to ratio of adherend thickness t to length L. Fu increases with t when t/L is less than 0.1 and hold as a constant when t/L is greater than 0.2; (2) Fu can well be predicted by bi-shear theory or maximum tension strain criterion, but not by Tresca and Mises criteria; (3) Although traditional approximate calculation method of connections is widely used, related experiment must be done for obtaining ultimate shearing stress. Thus, the fine analysis method presented in this paper is useful for stress analysis and strength evaluation of connections.
Authors: Yeong Huei Lee, Cher Siang Tan, M.Md. Tahir, Shahrin Mohammad, Poi Ngian Shek, Yee Ling Lee
Abstract: For the connection stiffness and strength prediction, Eurocode has showed an inadequacy as it will be affected by the thin-walled behaviour of cold-formed steel in actual structural performance. This paper performs a study on the connection stiffness prediction for cold-formed steel top-seat flange cleat connection with various angle thickness. Validated finite element modelling technique is applied for further advanced investigation. From the developed finite element models, it was realized that Eurocode has overestimated by the analytical stiffness prediction using component method for the studied connection which reduces the structural integrity in the design stage. A new proposal on connection stiffness prediction with influence of angle thickness for cold-formed steel top-seat flange cleat connection is presented to assist practicing engineers to design the cold-formed connection in light steel framing.
Authors: An Shun Cheng, Chung Ho Huang, Tsong Yen, Yong Lin Luo
Abstract: This research aims to investigate the pore structures and the interfacial transition zone (ITZ) of concrete containing both slag and fly ash. Test variables include three water-to-binder ratios (0.35, 0.50, 0.70) and four substitute ratios of cement with pozzolanic materials (20%, 30%, 50% and 60%). The specimens were tested to determine compressive strength, MIP porosity measurement and ITZ microhardness. Test results show that concrete containing slag and fly ash produce evident filling effect and the pozzolanic reaction after 28 days. At the age of 91 days the pozzolanic materials has provided prominent contribution to the strength, the porosity and the ITZ of concrete, making the pore volume smaller and ITZ property of pozzolanic concrete better than that of normal concrete. The concrete that adds suitable amount of pozzolanic materials (ex. 10% slag + 10% fly ash) has the optimum microstructure and mechanical property. Too much pozzolanic materials (ex. 40% slag + 20% fly ash) may be disadvantage to the concrete, and the suggested substitute ratio is under 50%. It is found that the compressive strength has the closest relationship with the total pore volume, so we use the total pore volume to predict the compressive strength of pozzolanic concrete and establish a prediction model as follow: S= -662.68Vt+87.29, R2=0.946.
Authors: Xiao Long Sui, Ming Sheng He, Xiao Jian Fu
Abstract: 16 groups of compressive strength with different mix proportion of lightweight heterogeneous soil mixed with expanded polystyrene (EPS-soil) has been gained by means of orthogonal test. Regression model is obtained, checked and evaluated by linear regression .48 groups of EPS-soil’s compressive strength is predicted by using strength predictable formula. Results show that: the formula’s precision is high and satisfy the actual need of project.
Authors: Long Li, Ping Hu, Wei Dong Li, Xiao Qiang Han
Abstract: Adhesive bonded single lap joints are used extensively in the manufacture of automobile structures. However, the joints involve many factors such as the overlap, the adherend thickness, the adherend yield strength etc. Therefore, strength prediction is a controversial issue. In order to quantify the effects of various variables, Latin Hypercube method was used to design the tests of simulation in the present study. The failure load predictive equation involving the factors of the overlap, the adherend thickness, the adherend yield strength, the adhesive thickness, the test speed and the adhesive toughness were achieved. The tests of single lap joints in tension load were carried on; while the results form experiments and formula were compared to verify its validation for strength prediction.
Authors: Raul D.S.G. Campilho, Marcelo F.S.F. de Moura, A.M.G. Pinto, Dimitra A. Ramantani, J.J.L. Morais, J.J.M.S. Domingues
Abstract: This work reports on the experimental and numerical study of the bending behaviour of two-dimensional adhesively-bonded scarf repairs of carbon-epoxy laminates, bonded with the ductile adhesive Araldite 2015®. Scarf angles varying from 2 to 45º were tested. The experimental work performed was used to validate a numerical Finite Element analysis using ABAQUS® and a methodology developed by the authors to predict the strength of bonded assemblies. This methodology consists on replacing the adhesive layer by cohesive elements, including mixed-mode criteria to deal with the mixed-mode behaviour usually observed in structures. Trapezoidal laws in pure modes I and II were used to account for the ductility of the adhesive used. The cohesive laws in pure modes I and II were determined with Double Cantilever Beam and End-Notched Flexure tests, respectively, using an inverse method. Since in the experiments interlaminar and transverse intralaminar failures of the carbon-epoxy components also occurred in some regions, cohesive laws to simulate these failure modes were also obtained experimentally with a similar procedure. A good correlation with the experiments was found on the elastic stiffness, maximum load and failure mode of the repairs, showing that this methodology simulates accurately the mechanical behaviour of bonded assemblies.
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