scholarly journals The Experimental Studies on Behavior of Ultrahigh-Performance Concrete Confined by Hybrid Fiber-Reinforced Polymer Tubes

2015 ◽  
Vol 2015 ◽  
pp. 1-18 ◽  
Author(s):  
Zong-cai Deng ◽  
Jiu-ling Qu
Keyword(s):  
Ultimate Strength ◽  
Experimental Studies ◽  
Strain Curve ◽  
Stress Strain ◽  
Explosive Failure ◽  
Linear Strengthening ◽  
Best Fitting ◽  
Reasonable Prediction ◽  
Frp Tube ◽  
Better Than

This paper conducts axial compression test of ultrahigh performance concrete- (UHPC-) filled hybrid FRP (HFRP) tubes, using the alternating hybrid technology to improve the deformation capacity of FRP tube and measure the axial compressive responses of ultimate strength, strains, and stress-strain curve of confined specimens. The test results show that the local rupture of HFRP tubes did not lead to explosive failure of UHPC cylinder, and its ductility is better than that of UHPC confined by only one type of FRP tube; HFRP tube can effectively improve the compressive strength and ultimate strain of UHPC specimens; the stress-strain curves divide into three distinct regions: linear phase, transition phase, and linear strengthening phase. None of the models provided a reasonable prediction for strength and strain of HFRP-confined UHPC specimen; therefore, a new ultimate strength and strain perdition model considering the confinement effectiveness of different hybrid FRP series was proposed. The new proposed model presented the best fitting results. The stress-strain responses predicted by the existing models are all below the experimental curves; therefore, a new three-stage constitutive model was proposed, which relatively fits the test curves better than the existing models.

scholarly journals Transformation of Surface Roughness of Mg Alloy Tubes During Laser Dieless Drawing

2020 ◽  
Vol 29 (11) ◽  
pp. 7736-7743
Author(s):  
Andrij Milenin ◽  
Tsuyoshi Furushima ◽  
Jiří Němeček
Keyword(s):  
Surface Roughness ◽  
Longitudinal Strain ◽  
Maximum Stress ◽  
Experimental Studies ◽  
Strain Curve ◽  
Surface Roughening ◽  
Drawing Process ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Dieless Drawing

AbstractThe paper investigates the transformation of surface roughness of tubes made from magnesium and magnesium alloys as a function of their longitudinal strain during laser dieless drawing. Experimental studies on three materials (AZ31, MgCa08, and pure Mg) have shown that the dependence of roughness on the longitudinal strain is nonlinear and exhibits a minimum. The proposed explanation for this is that the transformation of surface roughness occurs following two mechanisms. The first mechanism involves stretching of the tube and the decreasing of existing roughness with the increasing elongation. The second mechanism is based on the strain-induced surface roughening phenomenon. This mechanism leads to an increase in roughness with the increasing elongation. To analyze these mechanisms, a numerical model of roughness formation is used. It is experimentally shown that the position of the minimum roughness concerning the tube longitudinal strain is correlated with the stress-strain curve of the material under laser dieless drawing conditions. The obtained results provide a practical way to reduce surface roughness of tubes produced by the laser dieless drawing process. According to the proposed method, to achieve minimum roughness, it is necessary to keep the longitudinal strain under a specific value. This value is close to the strain, which corresponds to the maximum stress on the stress-strain curve of the material for temperature and strain rate, corresponding laser dieless drawing conditions.

A Three Dimensional Graphical Aid for Fatigue Data Analysis

2011 ◽  
Vol 488-489 ◽  
pp. 755-758 ◽  
Author(s):  
Bruno Atzori ◽  
Giovanni Meneghetti ◽  
Mauro Ricotta
Keyword(s):  
Experimental Data ◽  
Data Analysis ◽  
Three Dimensional ◽  
Strain Curve ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Compatibility Conditions ◽  
Stress Strain ◽  
Fatigue Data ◽  
Best Fitting

The fatigue behaviour of materials is usually synthesised in terms of stress-life (S-N) curve or in terms of strain-life (e-N) curve, the latter being described by the so-called Manson-Coffin equation. It is known that the assumption of equality of the plastic and elastic components between the Manson-Coffin and the stabilised stress-strain curves leads to the so-called compatibility conditions which connect the equations theoretically. The material constants of the Manson-Coffin and of the stabilised stress-strain curve are commonly determined by best fitting separately the experimental data obtained from strain-controlled fatigue tests. As a consequence the compatibility conditions may not be fulfilled. In this paper a method for fatigue data analysis that ensures the compatibility conditions is proposed and validated against experimental data.

Prediction of the Effective Stress-Strain Curves of Ductile Polymer 1D-Reinforced Composites Filled with Hollow Fibers Using Parameterized Model Based on Bezier Curves

2020 ◽  
Vol 833 ◽  
pp. 93-100
Author(s):  
Alexander Pavlovich Sokolov ◽  
Vitaliy Nikolaevich Schetinin ◽  
Arseniy Sergeevich Sapelkin ◽  
Mikhail Sergeevich Kuts ◽  
Konstantin Valerievich Mikhailovskiy
Keyword(s):  
Effective Stress ◽  
Experimental Studies ◽  
Strain Curve ◽  
Ductile Material ◽  
Compression Tests ◽  
Stress Strain ◽  
Bezier Curves ◽  
Bézier Curves ◽  
Model Based ◽  
Parameterized Model

The article presents the results of numerical and experimental studies of stress-strain curves of 1D-reinforced polymer composite materials based on hollow porous fibers and epoxy matrix. The two-scale nature of the composite under research was taken into account. A surrogate easily parameterized model based on Bezier curves was developed and used to approximate the stress-strain curve of ductile material. The calculations were performed using reversible homogenization and finite element methods, which were implemented in computational subsystem of DCS GCD. Representative volume elements of the investigated materials were created using the geometry generating subsystem of DCS GCD. Test samples were made using three-axis milling machine and compression tests were carried out. Computational results of effective stress-strain curves determination were obtained and compared with experiments.

Numerical and Experimental Study on Ultimate Strength of Stiffened Column Under Axial Compression

2020 ◽  
Author(s):  
Hongyuan Mei ◽  
Deyu Wang ◽  
Qi Wan
Keyword(s):  
Ultimate Strength ◽  
Axial Compression ◽  
Strain Curve ◽  
High Strength ◽  
Tensile Tests ◽  
True Stress ◽  
Stress Strain ◽  
Test Fixture ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

Abstract Six specimens with one Tee-bar stiffener and its attached plating were tested under axial compression to investigate the ultimate strength. The specimens have one longitudinal span and the simply supported boundary conditions at the end edge of loading were produced based on a horizontal test fixture. The initial geometrical imperfections were measured and tensile tests of high tensile steel used in the specimens with different thickness were conducted. The results calculated by FE analysis with true stress-strain curves, average measured thickness and measured initial geometrical deformation could reach a good agreement with experimental results. The ultimate strength calculated with elastic/perfectly plastic curve is approximately 10% larger than that with true stress-strain curve. The reason is that the proportional limit stress of material is significantly lower than 0.2% proof stress for the high strength steel used in specimens. And the occurrence of buckling is earlier than the time that the material enters into plastic stage. As a result, the ultimate strength assessed with elastic/perfectly plastic curve doesn’t always the lowest result and it should be adopted carefully.

Compression Behavior of Al-Mg Phases, Molecular Dynamics Simulation

2020 ◽  
Vol 46 ◽  
pp. 15-31 ◽  
Author(s):  
Hanae Chabba ◽  
Driss Dafir
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Deformation Behavior ◽  
Pure Aluminum ◽  
Experimental Studies ◽  
Strain Curve ◽  
Dynamics Simulation ◽  
Stress Strain ◽  
Elasticity Limit ◽  
Eam Potential

Aluminum alloys development always exit in the manufacturing process. Al/Mg alloys have been attracted significant attention because of their excellent mechanical properties. The microstructural evolution and deformation mechanisms are still challenging issues, and it is hard to observe directly by experimental methods. Accordingly, in this paper atomic simulations are performed to investigate the uniaxial compressive behavior of Al/Mg phases; with different ratio of Mg ranging from 31% to 56%. The compression is at the same strain rate (3.1010 s⁻¹), at the same temperature (300K) and pressure, using embedded atom method (EAM) potential to model the interactions and the deformation behavior between Al and Mg.From these simulations, we get the radial distribution function; the stress–strain responses to describe the elastic and plastic behaviors of β-Al3Mg2, ε-Al30Mg23, Al1Mg1 and γ-Al12Mg17 phases with 31, 41, 50 and 56% of Mg added to pure aluminum, respectively. The mechanical properties, such as Young’s modulus, elasticity limit and rupture pressure, are determined and presented. The engineering equation was used to plot the stress-strain curve for each phase.From the results obtained, the chemical composition has a significant effect on the properties of these phases. The stress-strain behavior comprised elastic, yield, strain softening and strain hardening regions that were qualitatively in agreement with previous simulations and experimental results. These stress-strain diagrams obtained show a rapid increase in stress up to a maximum followed by a gradual drop when the specimen fails by ductile fracture. Under compression, the deformation behavior of β-Al3Mg2 and γ-Al12Mg17 phases is slightly similar. From the results, it was found that ε-Al30Mg23 phase are brittle under uniaxial compressive loading and γ-Al12Mg17 phase is very ductile under the same compressive loading.The engineering stress-strain relationship suggests that β-Al3Mg2 and γ-Al12Mg17 phases have high elasticity limit, ability to resist deformation and also have the advantage of being highly malleable. From this simulation, we also find that the mechanical properties under compressive load of ε-Al30Mg23 phase are evidently less than other phases, which makes it the weakest phase. The obtained results were compared with the previous experimental studies, and generally, there is a good correlation.The Al-Mg system was built and simulated using molecular dynamics (MD) software LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator).

scholarly journals Investigation of Changes in Fatigue Damage Caused by Mean Load under Block Loading Conditions

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2738
Author(s):  
Roland Pawliczek ◽  
Tadeusz Lagoda
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Strain Curve ◽  
Mean Value ◽  
Fatigue Properties ◽  
Stress Strain ◽  
Reference Case ◽  
Block Loading ◽  
The Mean ◽  
Mean Strain

The literature in the area of material fatigue indicates that the fatigue properties may change with the number of cycles. Researchers recommend taking this into account in fatigue life calculation algorithms. The results of simulation research presented in this paper relate to an algorithm for estimating the fatigue life of specimens subjected to block loading with a nonzero mean value. The problem of block loads using a novel calculation model is presented in this paper. The model takes into account the change in stress–strain curve parameters caused by mean strain. Simulation tests were performed for generated triangular waveforms of strains, where load blocks with changed mean strain values were applied. During the analysis, the degree of fatigue damage was compared. The results of calculations obtained for standard values of stress–strain parameters (for symmetric loads) and those determined, taking into account changes in the curve parameters, are compared and presented in this paper. It is shown that by neglecting the effect of the mean strain value on the K′ and n′ parameters and by considering only the parameters of the cyclic deformation curve for εm = 0 (symmetric loads), the ratio of the total degree of fatigue damage varies from 10% for εa = 0.2% to 3.5% for εa = 0.6%. The largest differences in the calculation for ratios of the partial degrees of fatigue damage were observed in relation to the reference case for the sequence of block n3, where εm = 0.4%. The simulation results show that higher mean strains change the properties of the material, and in such cases, it is necessary to take into account the influence of the mean value on the material response under block loads.

scholarly journals Black rubber and the non-linear elastic response of scale invariant solids

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Matteo Baggioli ◽  
Víctor Cáncer Castillo ◽  
Oriol Pujolàs
Keyword(s):  
Strain Curve ◽  
Effective Field ◽  
Elastic Response ◽  
Elastic Behaviour ◽  
Scale Invariant ◽  
Stress Strain ◽  
Nonlinear Stress ◽  
Hyper Elastic ◽  
Simple Class ◽  
Nonlinear Elastic

Abstract We discuss the nonlinear elastic response in scale invariant solids. Following previous work, we split the analysis into two basic options: according to whether scale invariance (SI) is a manifest or a spontaneously broken symmetry. In the latter case, one can employ effective field theory methods, whereas in the former we use holographic methods. We focus on a simple class of holographic models that exhibit elastic behaviour, and obtain their nonlinear stress-strain curves as well as an estimate of the elasticity bounds — the maximum possible deformation in the elastic (reversible) regime. The bounds differ substantially in the manifest or spontaneously broken SI cases, even when the same stress- strain curve is assumed in both cases. Additionally, the hyper-elastic subset of models (that allow for large deformations) is found to have stress-strain curves akin to natural rubber. The holographic instances in this category, which we dub black rubber, display richer stress- strain curves — with two different power-law regimes at different magnitudes of the strain.

A modified version of MATLAB application window for predicting the weld bead profile and stress–strain plot of AA5052 CMT weldment using ER4043

SIMULATION ◽  
2021 ◽  
pp. 003754972110315
Author(s):  
B Girinath ◽  
N Siva Shanmugam
Keyword(s):  
Strain Curve ◽  
Weld Bead ◽  
Welding Parameters ◽  
Bead Geometry ◽  
Hybrid Technique ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Weld Bead Geometry ◽  
Inference System ◽  
Engineering Stress

The present study deals with the extended version of our previous research work. In this article, for predicting the entire weld bead geometry and engineering stress–strain curve of the cold metal transfer (CMT) weldment, a MATLAB based application window (second version) is developed with certain modifications. In the first version, for predicting the entire weld bead geometry, apart from weld bead characteristics, x and y coordinates (24 from each) of the extracted points are considered. Finally, in the first version, 53 output values (five for weld bead characteristics and 48 for x and y coordinates) are predicted using both multiple regression analysis (MRA) and adaptive neuro fuzzy inference system (ANFIS) technique to get an idea related to the complete weld bead geometry without performing the actual welding process. The obtained weld bead shapes using both the techniques are compared with the experimentally obtained bead shapes. Based on the results obtained from the first version and the knowledge acquired from literature, the complete shape of weld bead obtained using ANFIS is in good agreement with the experimentally obtained weld bead shape. This motivated us to adopt a hybrid technique known as ANFIS (combined artificial neural network and fuzzy features) alone in this paper for predicting the weld bead shape and engineering stress–strain curve of the welded joint. In the present study, an attempt is made to evaluate the accuracy of the prediction when the number of trials is reduced to half and increasing the number of data points from the macrograph to twice. Complete weld bead geometry and the engineering stress–strain curves were predicted against the input welding parameters (welding current and welding speed), fed by the user in the MATLAB application window. Finally, the entire weld bead geometries were predicted by both the first and the second version are compared and validated with the experimentally obtained weld bead shapes. The similar procedure was followed for predicting the engineering stress–strain curve to compare with experimental outcomes.

Sign in / Sign up

Export Citation Format

Share Document