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1

Estimating equibiaxial stress-strain relation based on non-homogeneous biaxial measurement

Havasi Kristóf, Kossa Attila

Journal of Theoretical and Applied Mechanics

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2025

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Vol. 63 nr 3

491--499

EN

This study investigates the influence of geometry on stress distributions in equibiaxial testing of rubber-like materials using hyperelastic models. Two geometries were examined, characterized by parameters specifying configurations like corner angles and normalized radii. A finite element approach was employed to simulate deformation under equibiaxial stretching, revealing non-homogeneous stress states. Apparent stress ratios were derived to evaluate geometry-induced deviations from purely equibiaxial stress-strain behavior. Results highlight the significance of geometrical factors in stress distributions. The findings offer insights for optimizing specimen designs for equibiaxial material characterization and improving the accuracy of extracted material properties.

2

Application of the numerical simulation method for the strength analysis of long-term portal crane components

Lipiec Sebastian, Zvirko Olha, Dzioba Ihor, Venhryniuk Oleh

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 4

126--139

EN

In this paper, the strength analysis of the material from two elements of a portal crane operated for about 33 years was carried out. The assessment was based on modelling and numerical simulation results using the finite element method of the load of three-point bending specimens. The constitutive relationships of the materials in the form of true stress-strain relationships were defined based on data from the uniaxial tensile test of the appropriate specimens. The iterative fitting method of the experimental and numerical relationship and the method that considers triaxiality and the Lode parameter were used. The accuracy of the defined stress-strain relationships was verified by comparing the load curves determined experimentally and numerically. Numerical modelling and simulation of the load of three-point bending specimens allowed obtaining stress distributions before the crack tip and the values of fracture toughness – J-integral. The results of the numerically calculated J-integral are similar to the experimental results. The trends in the stress component distributions indicate a high level of fracture toughness of the tested materials, ensuring a ductile nature of subcritical crack growth. The proposed methodology can be applied to other steels of operated structures.

3

Numerical simulation of weathered granite considering microporosity and mechanical parameter variations

Zhao Kang, Liu Yang, Ma Chao, Yan Yajing, Feng Yincheng, Tian Xiangqing, Chen Tong

Archives of Civil and Mechanical Engineering

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2024

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Vol. 24, no. 2

art. no. e119, 2024

EN

To study the deterioration of the mechanical properties of weathered granite and its damage characteristics under load, this paper carries out uniaxial compression and numerical simulation experimental research on fresh and weathered granite. The mechanical properties of fresh and weathered granite under uniaxial compression were analyzed, and the damage characteristics of weathered granite were revealed. Numerical models of different weathering degrees of the specimens were established based on FLAC3D, and at the same time, based on considering the distribution characteristics of granite microporosity, a random distribution model of weathered granite microporosity was established, and the deformation and damage laws of granite were obtained by numerical simulation. The results show that in the model considering the change of mechanical parameters of the rock in the weathering layer, the brittle tensile damage mainly occurs when the rock is not weathered. As weathering continues, the model undergoes brittle tensile and shear composite damage and gradually transitions to a damage pattern dominated by shear damage, which occurs when the rock strength deteriorates to about half of the fresh rock strength. In the model that jointly considers the mechanical parameters of rock microporosity and weathering layer, the microporosity affects the stress distribution to a certain extent, which leads to the change of the model strength and deformation damage characteristics. The damage form is closer to the real weathered rock damage, and the results of the study can provide a reference for the damage mode of weathered granite.

4

Properties of coarse mineral aggregates against properties of concrete

Piasta W., Budzyński W., Góra J.

Architecture Civil Engineering Environment

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2018

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Vol. 11, no. 3

97--105

EN

The paper concerns the effect of coarse aggregate type on the strength and strain properties of concrete under instantaneous loading. The studies deal with properties of the crushed aggregates and their effect on the basic mechanical properties and instant deformability of concretes in comparison to gravel concrete. The paper presents test results of mineral composition, crushing strength, absorption by weight, content of irregular grains and mineral dust as well as bulk and specific density of the 5 coarse aggregates: basalt, granite, dolomite, quartzite and natural aggregate (gravel) derived from the Polish rock beds. Strength and strain properties of concretes under compressive instantaneous loading were analyzed. The analysis showed that strength properties and modules of elasticity of tested concretes are proportional to crushing strength of aggregates. Based on the test results of strains it was concluded that the effect of coarse aggregate type on the modulus of elasticity and the limit strain is more significant than that of concrete strength.

5

Mathematical and Experimental Analysis Tension of Steel in Bi-Polar Coordinates

Jaroniek M.

Mechanics and Mechanical Engineering

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2016

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Vol. 20, nr 4

467--488

EN

A series of experiments was carried out to examine the effects of elastic–plastic deformation on the state of stress and the flow stress mechanism under static tension. The strain distribution determined from the fringe pattern using the Moire method allows one to determine the strain and the crack propagation of not–notched specimens an isotropic and elastic–plastic materials. In the analysis of stress the method of calculating using the bipolar coordinate is proposed. The theoretical model is divided into two elements and the condition of incompressibility is satisfied in each element. The proposed method is compared with the elastic-plastic FEM (ANSYS 12, 14) and it is satisfied approximately. The tensile test is aimed to verify the mathematical model that can be applied in the logarithmic stain in further computations.

6

Odkształcalność zbrojenia w elementach żelbetowych narażonych na warunki pożarowe

Kisieliński R., Kowalski R., Abramowicz M.

Materiały Budowlane

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2016

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nr 8

140--144

PL

W artykule omówiono wpływ wysokiej temperatury na odkształcalność współcześnie stosowanej w Polsce stali zbrojeniowej. W przeszłości pręty używane do zbrojenia betonu miały jednorodny rozkład właściwości mechanicznych w przekroju poprzecznym, natomiast obecnie tak nie jest w przypadku produkcji z zastosowaniem technologii umacniania cieplnego. Może więc powstać wątpliwość, czy odkształcenia współcześnie stosowanej stali zbrojeniowej w warunkach pożarowych będą zgodne z określonymi na podstawie modelu podanego w PN-EN 1992‑1‑2. Model ten zaproponowano ponad ćwierć wieku temu, na podstawie wyników badań innego rodzaju stali, przeprowadzonych w warunkach ustalonej temperatury, a więc innych niż występujące podczas pożaru, kiedy temperatura nie jest ustalona. W artykule przedstawiono wyniki badań prętów średnicy 10, 12 i 16 mm, ze stali gatunku B500SP, w warunkach ustalonej i nieustalonej (wzrastającej) temperatury. Odpowiednie składniki całkowitego odkształcenia prętów uzyskane w badaniach przeprowadzonych w warunkach ustalonej i nieustalonej temperatury okazały się do siebie zbliżone i zgodne z określonymi na podstawie modelu PN-EN 1992-1-2. Nie zaobserwowano też istotnych różnic między wynikami badań prętów w przypadku poszczególnych średnic.

EN

In this paper the influence of high temperature on the elongation of the reinforcing steel currently used in Poland is analysed. Steel bars used in the past to reinforce concrete had a uniform distribution of mechanical properties in a cross-section. However, bars used nowadays are produced with the use of quenching and self-tempering process and are characterized by a non-uniform distribution of these properties. Therefore, it is unlikely that modern bar elongation at high temperature will be in a good accordance with Eurocode 1992‑1‑2 prediction. Eurocode model was proposed more than 25 years ago on the basis of tests of a different kind of steel, performed in steady temperature conditions (which are different than those in a real fire when temperature is increasing). The paper presents test results performed in steady and increasing temperature conditions, on B500SP steel bars 10, 12 and 16 mm in diameter. Corresponding parts of the overall bar strain obtained in both tests have been found to be similar to each other and consistent with those predicted by the Eurocode 1992-1-2 model. No significant differences were found between the results of tests of various diameter bars.

7

Model zbrojenia obciążonego cyklicznie z uwzględnieniem niesprężystego wyboczenia

Korentz J.

Przegląd Budowlany

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2012

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R. 83, nr 5

141-143

PL

W artykule przedstawiono nowy model fizyczny zbrojenia obciążonego cyklicznie z uwzględnieniem jego niesprężystego wyboczenia. W modelu tym opisuje się związki między naprężeniami a odkształceniami jedynie dla obwiedni pętli histerezy.

EN

This article presents a new physical model of reinforcement subjected to cyclic loading, taking account of its inelastic buckling. In this model the relations between stresses and deformations are described only for the envelope of the hysteresis loop.

8

Plastic stresses, strains and the phase of failure in tension

Jaroniek M.

Mechanics and Mechanical Engineering

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2006

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Vol. 10, nr 1

82-109

EN

In this paper the analysis of the state of strain and stress in necking has been analysed. A description of the stress-strain relationship, which takes into account strain hardening, and next necking until the moment of rupture, along with a description of breaking stresses, allows one to build such a mathematical model (described in bi-polar coordinates) in the whole range of load, which accounts for the fracture formation and the element failure.