@article { author = {Dabbagh, H. and Nosoudi, A. and Mohammad Doost, H.}, title = {Linear Numerical Stress Analysis of Concrete Specimens under Different Direct Tension Test Setups}, journal = {Journal of Stress Analysis}, volume = {1}, number = {2}, pages = {1-12}, year = {2017}, publisher = {Bu-Ali Sina University}, issn = {2588-2597}, eissn = {2588-3054}, doi = {10.22084/jsa.2017.12251.1011}, abstract = {Tensile strength is one of the basic and important mechanical properties of concrete. The measurement of the tensile strength of concrete is not easy. This is because this property of concrete is dependent on the different test setups that must be used. Indirect methods have been used hitherto to measure tensile strength of concrete. These methods though widely accepted, do not provide the true tensile strength of concrete in comparison with direct methods. According to this, the present study focuses on the analytical and experimental investigation of the prismatic concrete specimensunder direct tension test setups. In this paper, different test setups were studied to produce a more uniform tensile stress distribution and minimize stress concentration at both ends of the concrete specimens with normal compressive strength. ABAQUS software was employed to carry out the finite element analysis of the concrete specimens under direct tension test setups.}, keywords = {Direct tension,tensile strength,Tensile stress distribution,Finite element analysis,ABAQUS}, url = {https://jrstan.basu.ac.ir/article_1913.html}, eprint = {https://jrstan.basu.ac.ir/article_1913_c7f4ba1b2657e1dab3745fa01eebb549.pdf} } @article { author = {Fariba, F. and Ahmadpour, M. and Bahrami, H.}, title = {A New Method for Correcting the Stress-Strain Curves after Bulging in Metals}, journal = {Journal of Stress Analysis}, volume = {1}, number = {2}, pages = {13-23}, year = {2017}, publisher = {Bu-Ali Sina University}, issn = {2588-2597}, eissn = {2588-3054}, doi = {10.22084/jsa.2017.12608.1013}, abstract = {True stress-strain curve has a basic role in the analysis of deformation in theoretical plasticity and numerical simulations. Because of the triaxial state of stresses in the necking or bulging zones, in tension and the compression tests respectively, the true stress-strain curves obtained from relationsare no longer valid and must be corrected. Various correction techniques have been proposed and can be found in literatures. In this study, a new semi-analytical approach for correction of the stress-strain curve in compression test for circular cross-section specimens was introduced and a relation for the correction factor was derived based on the theory of plasticity. This relation requires only a few experimental surface strain measurements which can easily be done using an image processing technique. The correction factor formula was obtained in terms of the initial radius of specimen, the bulge radius, and the surface strain on the bulge surface. The proposed approach in this study was compared with the results of the numerical simulations. Simulation was used to correct the stress-strain curve based on the optimization method with comparing the bulging profile of tested samples and ones simulated by using genetic algorithm. }, keywords = {Stress-strain curve,Correction factor,Image processing method,Numerical simulation}, url = {https://jrstan.basu.ac.ir/article_1914.html}, eprint = {https://jrstan.basu.ac.ir/article_1914_5d8c6bee681805f82a5c8c3b23b336e9.pdf} } @article { author = {Feli, S. and Aalami Aaleagha, M.E. and Jahanban, M.R.}, title = {Evaluation Effects of Modeling Parameters on the Temperature Fields and Residual Stresses of Butt-Welded Stainless Steel Pipes}, journal = {Journal of Stress Analysis}, volume = {1}, number = {2}, pages = {25-33}, year = {2017}, publisher = {Bu-Ali Sina University}, issn = {2588-2597}, eissn = {2588-3054}, doi = {10.22084/jsa.2017.11132.1002}, abstract = {In this paper, the effects of modeling parameters on the temperature field and residual stresses of butt-welded stainless steel pipes were investigated by using finite element modeling in ABAQUS code. The investigated parameters included, heat flux distribution, latent heat, and heat flux type. The birth and death techniques were utilized to consider mass addition from Y308L filler metal into the weld pool. The moving heat source and convection heat transfer were also modeled by a user subroutine DFLUX and FILM in ABAQUS code. In this work, for verification of FE modeling the temperature fields and residual stresses were compared with available experimental results. The simulation results showed that heat flux with a double ellipsoidal distribution proposed by Goldak associated with latent heat parameter and employed a fully volumetric arc heat input, representing the best match with the experimental data.}, keywords = {Residual stress,Butt-welded,Stainless steel pipe,Temperature field}, url = {https://jrstan.basu.ac.ir/article_1915.html}, eprint = {https://jrstan.basu.ac.ir/article_1915_e5e0e65911ace9dc6ca8eb1b07d87834.pdf} } @article { author = {Haghighat, H. and Janghorban, A.}, title = {An Analytical Model for Long Tube Hydroforming in a Square Cross-Section Die Considering Anisotropic Effects of the Material}, journal = {Journal of Stress Analysis}, volume = {1}, number = {2}, pages = {35-41}, year = {2017}, publisher = {Bu-Ali Sina University}, issn = {2588-2597}, eissn = {2588-3054}, doi = {10.22084/jsa.2017.11676.1009}, abstract = {In this paper, a mathematical model was developed to analyze the hydroforming process of a long anisotropic circular tube into a square cross-section die. By using the thickness variation in two extreme cases of friction between the tube and die wall, namely no friction and sticking friction cases, thickness variation in the case of sticking friction was captured in the model. Then by using equilibrium equation for contact length segment, thickness distribution was determined and corresponding forming pressure is predicted. It was shown that in a plane strain state, anisotropic value has no influence on thickness variation of the deformed tube and the forming pressure will increase when the anisotropic value increases. The analytical results of forming pressures and thickness distributions were compared with the results available in theliterature to verify the validity of this simple analytical proposed model.}, keywords = {Tube hydroforming,Anisotropic,Square cross-section die}, url = {https://jrstan.basu.ac.ir/article_1916.html}, eprint = {https://jrstan.basu.ac.ir/article_1916_17d097ab9e40e4b4fdea29eef024c5cf.pdf} } @article { author = {Pak, A. and Abdullah, A.}, title = {An Approach to Designing a Dual Frequency Piezoelectric Ultrasonic Transducer}, journal = {Journal of Stress Analysis}, volume = {1}, number = {2}, pages = {43-53}, year = {2017}, publisher = {Bu-Ali Sina University}, issn = {2588-2597}, eissn = {2588-3054}, doi = {10.22084/jsa.2017.12630.1014}, abstract = {This paper has been devoted to such approach for designed and fabricated the dual frequency piezoelectric ultrasonic transducer having longitudinal vibrations for high power application. By using analytical analysis, the resonance frequency equations of the transducer in the half-wave and the all-wave vibrational modes were determined for the assumed first resonance frequency of 25kHz. According to the resonance frequency equation, four transducers with two different constructions (Type A and B) were designed and made. The finite element method provided by commercial ANSYS was employed for FEM modeling and analysis of the transducer to observe its vibration behavior. It was shown that there is a good agreement between the experimental and FEM results. The designed and fabricated transducer can be excited to vibrate at two resonance frequencies, which correspond to the half-wave and the all-wave vibrational modes of the transducer, and use of Type B transducer greatly increased the mechanical quality factor (Q) of piezoelectric transducers.}, keywords = {Dual frequency ultrasonic transducer,High power ultrasonic,FEM simulation,Ultrasonic cleaning}, url = {https://jrstan.basu.ac.ir/article_1917.html}, eprint = {https://jrstan.basu.ac.ir/article_1917_924fed9d8c264974ea50d9026d453b36.pdf} } @article { author = {Salimi, M.H. and Assadollahi, M. and Nakhodchi, S.}, title = {Failure Mechanism and Ultimate Strength of Friction Stir Spot Welded Al-5052 Joints under Tensile-shear Loading}, journal = {Journal of Stress Analysis}, volume = {1}, number = {2}, pages = {55-61}, year = {2017}, publisher = {Bu-Ali Sina University}, issn = {2588-2597}, eissn = {2588-3054}, doi = {10.22084/jsa.2017.12922.1020}, abstract = {In this paper failure mechanism of a joint which was welded by friction stir spot welding method was studied. The 5052 aluminum joint was loaded under tensile-shear condition.To find out failure mechanism, several tests were conducted such as: strain-stress, macrography, and Vickers hardness. Results of strain-stress test state the stages of failure and crack initiation and propagation. Macrography analysis was done in several stages with different penetration depths. It was shown that the material flow, the critical surface of the coupon, and the determined zones were more possible to generate crack. Finally, by using Vickers hardness test, the susceptible zones to crack generation and propagation can be specified.}, keywords = {FSSW,Failure mechanism,analysis,tensile-shear load}, url = {https://jrstan.basu.ac.ir/article_1918.html}, eprint = {https://jrstan.basu.ac.ir/article_1918_18b8f51e9ddbcc159e4b61a449a76008.pdf} }