Estimation of the cyclic shear stress-strain curve from tensile properties for steels

2018 ◽  
Vol 49 (11) ◽  
pp. 1346-1352 ◽  
Author(s):  
J. Li ◽  
C.W. Li ◽  
Z.P. Zhang
Author(s):  
Xiuhan Yang ◽  
Sai Vanapalli

Several of the geotechnical structures constructed with unsaturated soils undergo a large deformation prior to reaching failure conditions (e.g. progressive failure of a soil slope). During this process, the shear stress in soils typically increases initially and then reduces with an increase in the shear strain. The prediction of the stress-strain relationship is critical for reasonable interpretation of the mechanical behavior of those geo-structures that undergo large deformation. This paper introduces a model based on the disturbed state concept (DSC) to predict the variation of shear stress in unsaturated soils during strain-softening process under consolidated drained triaxial compression condition. In this model, the apparent stress-strain relationship is formulated as a weighted average of a hyperbolic hardening response extending the pre-peak state stress-strain curve and a linear response extending the critical state stress-strain curve with an assumed disturbance function as the weight. The prediction procedure is described in detail and the proposed model is validated using several sets of published data on unsaturated soils varying from coarse- to fine-grained soils. Finally, a comprehensive error analysis is undertaken based on an index of agreement approach.


2010 ◽  
Vol 457 ◽  
pp. 114-119 ◽  
Author(s):  
Fredrik Wilberfors ◽  
Ingvar L. Svensson

The main purpose with this paper is to show the effect of nitrogen and inoculation on the tensile properties and microstructure of cast iron with lamellar graphite. Casting experiments were performed with the main composition: 3.4 % C, 2.0 % Si, 0.7 % Mn, 0.5 % Cu. The nitrogen content was varied between 90-180 ppm and inoculant was added as 0, 0.2 or 0.4 % by weight. The addition of inoculant changed the graphite structure from distribution D/B/A to distribution A, according to ISO 945. The eutectic cell size decreased significantly. The addition of inoculant had no influence on the hardness. The addition of nitrogen shortened the graphite flakes and increased the hardness. The influence on the eutectic cell size was low and there was no significant effect on the graphite distribution. Tensile test samples were analysed by true stress – true plastic strain in terms of the flow relationships proposed by Hollomon, , and Ludwigson, . The stress-strain curves were fitted to polynomial functions of the 6:th to 8:th order before evaluating the constants in order to eliminate noise from the measurements. This approach also enabled the slope of the stress-strain curve to be evaluated at zero stress (Young’s modulus), resulting in plastic strain from stress levels close to zero. The Hollomon flow relationship failed to describe the deformation behaviour for the whole range of the stress-strain curve. The correction terms in the Ludwigson flow relationship resulted in a better fit. The addition of inoculant mainly affected the strength coefficient, . The addition of nitrogen also affected the constant. The main reason for this was that the addition of inoculant influenced the last part of the stress-strain curve while the addition of nitrogen had an effect over the whole range of the curve. The addition of nitrogen and inoculant increased the tensile strength from 288 MPa to 393 MPa and the total elongation at fracture from 0.8 % to 1.6 %.


1997 ◽  
Vol 119 (2) ◽  
pp. 81-84 ◽  
Author(s):  
A. Gilat ◽  
K. Krishna

A new configuration for testing thin layers of solder is introduced and employed to study the effects of strain rate and thickness on the mechanical response of eutectic Sn-Pb solder. The solder in the test is loaded under a well defined state of pure shear stress. The stress and deformation in the solder are measured very accurately to produce a reliable stress-strain curve. The results show that both the stress needed for plastic deformation and ductility increase with increasing strain rate.


2012 ◽  
Vol 238 ◽  
pp. 41-45
Author(s):  
Hong Yuan Huo ◽  
Chen Jie Cao ◽  
Li Sun ◽  
Li Sha Song ◽  
Tong Xing

The tests were carried out to study the effects of the fraction of steel fiber by volume and the thickness of cement paste wrapping steel fibers on the axial tensile properties of steel fiber reinforced concrete (SFRC). The strength grade of SFRC was CF40 with the fraction of steel fiber by volume varying from 0.5% to 2.0%, and the thickness of cement paste wrapping steel fibers varying from 0.8mm to 1.2mm. The tests were conducted by WAW-600 electric-hydraulic servo-type test machine. The results show that the axial tensile properties such as the axial tensile strength, the fullness of stress-strain curve, the tensile energy and the axial tensile toughness ratio are all improved obviously by the adding of steel fiber in concrete. The reasonable thickness of cement paste wrapping steel fibers is 1.0mm. The formulas for stress-strain relationship of SFRC in axial tension are proposed.


1965 ◽  
Vol 18 (3) ◽  
pp. 689 ◽  
Author(s):  
RE Chapman

Poorly crimped (or doggy) fibres, produced by follicles with hyperplasia of the outer root sheath tissue, have greater proportions of paracortex than adjacent well-crimped fibres. Associated with this increase in paracortex is an increase in strength, as indicated by significant increases in the stresses in wet poorly crimped fibres at the turnover and breaking points on the stress-strain curve. Use of the stronger mechanical properties of doggy fibres as a means of distinguishing such fibres from the poorly crimped fibres in steely wool, produced by sheep on a copper-deficient diet, is proposed.


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