Non-linear compression stress-strain curve of pitch-based high modulus carbon fibre composites and structural responses

1992 ◽  
Vol 27 (14) ◽  
pp. 3782-3788 ◽  
Author(s):  
N. Tsuji ◽  
K. Kubomura
Keyword(s):  
Carbon Fibre ◽  
Strain Curve ◽  
Compression Stress ◽  
High Modulus ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Fibre Composites ◽  
Non Linear ◽  
Structural Responses ◽  
Carbon Fibre Composites

scholarly journals Dynamic Characteristics of Sandstone under Coupled Static-Dynamic Loads after Freeze-Thaw Cycles

2020 ◽  
Vol 10 (10) ◽  
pp. 3351
Author(s):  
Bo Ke ◽  
Jian Zhang ◽  
Hongwei Deng ◽  
Xiangru Yang
Keyword(s):  
Energy Absorption ◽  
Dynamic Characteristics ◽  
Shear Failure ◽  
Strain Curve ◽  
Peak Stress ◽  
Peak Strain ◽  
Compression Stress ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Freeze Thaw

The effect of temperature fluctuation on rocks needs to be considered in many civil engineering applications. Up to date the dynamic characteristics of rock under freeze-thaw cycles are still not quite clearly understood. In this study, the dynamic mechanical properties of sandstone under pre-compression stress and freeze-thaw cycles were investigated. At the same number of freeze-thaw cycles, with increasing axial pre-compression stress, the dynamic Young’s modulus and peak stress first increase and then decrease, whereas the dynamic peak strain first decreases and then increases. At the same pre-compression stress, with increasing number of freeze-thaw cycles, the peak stress decreases while the peak strain increases, and the peak strain and peak stress show an inverse correlation before or after the pre-compression stress reaches the densification load of the static stress–strain curve. The peak stress and strain both increase under the static load near the yielding stage threshold of the static stress–strain curve. The failure mode is mainly shear failure, and with increasing axial pre-compression stress, the degree of shear failure increases, the energy absorption rate of the specimen increases first and then decreases. With increasing number of freeze-thaw cycles, the number of fragments increases and the size diminishes, and the energy absorption rates of the sandstone increase.

Experimental Setup for the Determination of Mechanical Solder Materials Properties at Elevated Temperatures

2010 ◽  
Vol 638-642 ◽  
pp. 3793-3798
Author(s):  
Wolfgang H. Müller ◽  
Holger Worrack ◽  
Jens Sterthaus
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Elevated Temperatures ◽  
Young's Modulus ◽  
Linear Optimization ◽  
Strain Curve ◽  
Stress And Strain ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Non Linear

The fabrication of microelectronic and micromechanical devices leads to the use of only very small amounts of matter, which can behave quite differently than the corresponding bulk. Clearly, the materials will age and it is important to gather information on the (changing) material characteristics. In particular, Young’s modulus, yield stress, and hardness are of great interest. Moreover, a complete stress-strain curve is desirable for a detailed material characterization and simulation of a component, e.g., by Finite Elements (FE). However, since the amount of matter is so small and it is the intention to describe its behavior as realistic as possible, miniature tests are used for measuring the mechanical properties. In this paper two miniature tests are presented for this purpose, a mini-uniaxial-tension-test and a nanoindenter experiment. In the tensile test the axial load is prescribed and the corresponding extension of the specimen length is recorded, both of which determines the stress-strain- curve directly. The stress-strain curves are analyzed by assuming a non-linear relationship between stress and strain of the Ramberg-Osgood type and by fitting the corresponding parameters to the experimental data (obtained for various microelectronic solders) by means of a non-linear optimization routine. For a detailed analysis of very local mechanical properties nanoindentation is used, resulting primarily in load vs. indentation-depth data. According to the procedure of Oliver and Pharr this data can be used to obtain hardness and Young’s modulus but not a complete stress-strain curve, at least not directly. In order to obtain such a stress-strain-curve, the nanoindentation experiment is combined with FE and the coefficients involved in the corresponding constitutive equations for stress and strain are obtained by means of the inverse method. The stress-strain curves from nanoindentation and tensile tests are compared for two mate-rials (aluminum and steel). Differences are explained in terms of the locality of the measurement. Finally, material properties at elevated temperature are of particular interest in order to characterize the materials even more completely. We describe the setup for hot stage nanoindentation tests in context with first results for selected materials.

Tension-compression stress-strain curves from bending tests

1971 ◽  
Vol 6 (4) ◽  
pp. 286-292 ◽  
Author(s):  
P W J Oldroyd
Keyword(s):  
Strain Curve ◽  
Bending Moment ◽  
Uniaxial Stress ◽  
Bending Test ◽  
Compression Stress ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Bending Tests ◽  
Original Length ◽  
Annealed Copper

A formula—Nadai's bending formula—is derived which enables the tension (or compression) stress-strain curve for a material to be obtained from the curve relating bending moment to curvature for a beam of solid rectangular section. The method is extended to give a formula which covers deformations in which reversals of plastic strain occur. The results obtained from a unidirectional bending test made on annealed copper are compared with those obtained from a tensile test made on the same material and the accuracy of the stress-strain values obtained from the bending test is discussed. The results obtained from a reversed bending test are also compared with those obtained from a tension-compression test in which a specimen was first stretched and then compressed to its original length. The limitations imposed by this method of obtaining the stress-strain curve for a material are examined and the advantages its presents in the study of the behaviour of materials under uniaxial stress are outlined.

Non-linear delamination fracture analysis by using power-law hardening

2016 ◽  
Vol 12 (1) ◽  
pp. 80-92 ◽  
Author(s):  
Victor Iliev Rizov
Keyword(s):  
Power Law ◽  
Strain Curve ◽  
Fracture Analysis ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Content Type ◽  
Elastic Plastic ◽  
Linear Fracture ◽  
Delamination Fracture ◽  
Non Linear

Purpose – The purpose of this paper is to perform a theoretical analysis of non-linear delamination fracture in cantilever beam opened notch (CBON) configuration. It is assumed that the non-linear mechanical behavior of the CBON can be described by using a stress-strain curve with power-law hardening. Design/methodology/approach – The fracture analysis is carried-out by applying the integration contour independent J-integral. For this purpose, a model based on the technical beam theory is used. Equation is derived for determination of the CBON specimen curvature in elastic-plastic stage of deformation. The equation is solved by using the MatLab program system. Solutions of the J-integral are obtained at linear-elastic as well as elastic-plastic behavior of the CBON. The influence of the power-law exponent on the non-linear fracture is evaluated. Findings – The analysis reveals that the J-integral value increases when the exponent of the power-law increases. The solution obtained here is very useful for parametric analyses of the non-linear fracture behavior, since the simple formulas derived capture the essentials of the fracture response. Practical implications – Beside for parametric investigations, the solution obtained here can also be applied for calculating the critical J-integral value at non-linear behavior using experimentally determined critical fracture load at the onset of crack growth from the initial crack tip position in the CBON configuration. Originality/value – An analysis is performed of the non-linear fracture in the CBON configuration by applying the J-integral approach, assuming that the mechanical response can be modeled using a stress-strain curve with power-law hardening.

Delamination analysis of a layered elastic-plastic beam

2017 ◽  
Vol 8 (5) ◽  
pp. 516-529 ◽  
Author(s):  
Victor Rizov
Keyword(s):  
Fracture Behaviour ◽  
Strain Curve ◽  
Integral Approach ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Content Type ◽  
Elastic Plastic ◽  
Lap Shear ◽  
Delamination Fracture ◽  
Non Linear

Purpose The purpose of this paper is to perform a theoretical analysis of delamination fracture behaviour of the Crack Lap Shear layered beam configuration taking into account the material non-linearity. A delamination crack located arbitrarily along the beam height was considered in this study. Design/methodology/approach The beam mechanical behaviour was described by using the Ramberg-Osgood stress-strain relation. Fracture was analysed by applying the J-integral approach. Besides by using symmetric Ramberg-Osgood stress-strain curve, fracture was investigated also by Ramberg-Osgood stress-strain curve that is not symmetric with respect to tension and compression. The J-integral solutions were verified by performing elastic-plastic analyses of the strain energy release rate. Findings The effects of crack location and material properties on the non-linear fracture behaviour were evaluated. It was found that the material non-linearity leads to increase of the J-integral values. Therefore, the material non-linearity has to be taken into account in fracture mechanics based safety design of structural members composed by layered materials. The analytical solutions derived are very useful for parametric investigations of delamination fracture with considering the material non-linearity. The results obtained can be applied for optimisation of the beam structure with respect to fracture performance. Originality/value The present study contributes for the understanding of delamination fracture in layered beams that exhibit non-linear material behaviour.

scholarly journals A 3-D finite element modeling for the textile-reinforced concrete plates under tensile load using a non-linear behaviour for cementitious matrix

2021 ◽  
Vol 15 (1) ◽  
pp. 67-78
Author(s):  
Tran Manh Tien ◽  
Xuan Hong Vu ◽  
Dao Phuc Lam ◽  
Pham Duc Tho
Keyword(s):  
Reinforced Concrete ◽  
Mechanical Behavior ◽  
Tensile Load ◽  
Strain Curve ◽  
Numerical Results ◽  
Textile Reinforced Concrete ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Cementitious Matrix ◽  
Non Linear

A big question in the numerical approaches for the mechanical behavior of the textile-reinforced concrete (TRC) composite under tensile loading is how to model the cracking of the cementitious matrix. This paper presents numerical results of 3-D modeling of TRC composite in which the non-linear behavior model was used by considering the cracking for the cementitious matrix. The input data based on the experimental results in the literature. As numerical results, the TRC composite provides a strain-hardening behavior with three phases in which the second one is characterized by the drops in stress on the stress-strain curve. Furthermore, this model could show the failure mode of the TRC specimen with the multi-cracking on its surface after the numerical tests. From this model, the development of a crack from micro-crack to macro at a cross-section was highlighted. The stress jumps in reinforcement textile after each crack was also observed and analyzed. In comparison with the experiment, a good agreement between both results was found for all cases of this study. A parametric study could show the effect of the length and position of the measurement zone on the stress-strain curve of TRC’s mechanical behavior. Keywords: textile reinforced concrete (TRC); cementitious matrix; textile reinforcement; mechanical behaviour; numerical modeling.

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