Nelson Arzola
National University of Colombia
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Featured researches published by Nelson Arzola.
Materials | 2018
Oscar Araque; Nelson Arzola
The objective of this research is to develop an experimental-theoretical analysis about the influence of the cooling medium and the geometry of the welding bead profile in fatigue life and the associated parameters with structural integrity of welded joints. A welded joint with cruciform geometry is considered using SMAW (Shielded Metal ArcWelding), plates in structural steel ASTM A36 HR of 8 mm of thickness, and E6013 electrode input. A three-dimensional computational model of the cruciform joint was created using the finite element method. For this model, the surface undulation of the cord and differentiation in the mechanical properties of the fusion zone were considered, the heat-affected zone (HAZ) and base material, respectively. In addition, an initial residual stress field, which was established experimentally, was considered. The results were a set of analytical expressions for the weld magnification factor Mk. It was found that values for the latter decrease markedly in function of the intensity of the cooling medium used in the post welding cooling phase, mainly due to the effect of the residual compressive stresses. The obtained models of behavior of the weld magnification factor are compared with the results from other researchers with some small differences, mainly due to the inclusion of the cooling effect of the post weld and the variation of the leg of the weld bead. The obtained analytical equations in the present research for Mk can be used in management models of life and structural integrity for this type of welded joint.
Materials | 2018
Oscar Araque; Nelson Arzola; Edgar Hernández
This research deals with the fatigue behavior of butt-welded joints, by considering the geometry and post-welding cooling cycles, as a result of cooling in quiet air and immersed in water. ASTM A-36 HR structural steel was used as the base metal for the shielded metal arc welding (SMAW) process with welding electrode E6013. The welding reinforcement was 1 mm and 3 mm, respectively; axial fatigue tests were carried out to determine the life and behavior in cracks propagation of the tested welded joints, mechanical characterization tests of properties in welded joints such as microhardness, Charpy impact test and metallographic analysis were carried out. The latter were used as input for the analysis by finite elements which influence the initiation and propagation of cracks and the evaluation of stress intensity factors (SIF). The latter led to obtaining the crack propagation rate and the geometric factor. The tested specimens were analyzed, by taking photographs of the cracks at its beginning in order to make a count of the marks at the origin of the crack. From the results obtained and the marks count, the fatigue crack growth rate and the influence of the cooling media on the life of the welded joint are validated, according to the experimental results. It can be concluded that the welded joints with a higher weld reinforcement have a shorter fatigue life. This is due to the stress concentration that occurs in the vicinity of the weld toe.
Journal of Physics: Conference Series | 2017
Nelson Arzola; Edgar Hernández
In this work the experimental characterization of fatigue strength in butt welded joints considering the geometry and the post-weld cooling cycle was performed. ASTM A-36 structural steel was used as the base metal for the shielded metal arc welding process, with welding electrode E6013. Two experimental factors were established: weld bead geometry and the post-weld cooling rate. Two levels for each factor, the welding reinforcement (1 and 3 mm), and the rate of cooling, slow (quiet air) and fast (immersion in water) are evaluated respectively. For the uniaxial fatigue tests, 8 samples were selected for each treatment for a total of 32 specimens. The mechanical and fractomechanical properties of fusion zone, heat affected zone and base metal in relation to the analysis of failure mechanisms were analysed. The fatigue crack growth rates were estimated based on the counting of microstrations. Furthermore, experimental tests, such as uniaxial tension, microindentation hardness, Charpy impact and metallographic analysis, were made to know the influence of the experimental factors in the fatigue strength. On this research, about the 78.13% of the samples obtained a resistance higher than the recommended one by class FAT 100. The results showed that the geometry of the joint is the factor of greatest influence on fatigue strength for butt welded joints; the greater the weld reinforcement the lower the fatigue strength of the joint. Although it is also important to consider other geometric factors of less impact as it is the weld toe radius and the welding chord width.
2014 III International Congress of Engineering Mechatronics and Automation (CIIMA) | 2014
Diego Alejandro Aguirre; Ivan Ricardo Duquino; Alirio Jimenez Franco; Raul Giordano Soto; Nelson Arzola; Liz Karen Herrera; Andres Fernando Gil Plazas
In order to participate in the Formula SENA ECO, which is a national design and race performance competition using electric drive system vehicles, these must be lightweight, have a lower drag coefficient and high energy efficiency. An engineering redesign has been developed at the vehicle rear section using the CATIA PLM-tool, providing an optimized solution which focuses on main issues and needs such as the resistance to the powertrain components, loading conditions like weights and inertias, among others static and dynamic loads that submit the chassis structure to stress. Design analysis and graphs results obtained from the design tool are presented.
Dyna | 2011
Jair Leopoldo Loaiza; Nelson Arzola
Revista Ingenieria E Investigacion | 2012
Nelson Arzola; Alexander Gómez; Sonia Rincön
Journal of The Brazilian Society of Mechanical Sciences and Engineering | 2015
Dennis León; Nelson Arzola; Andres Tovar
Global Nest Journal | 2014
Nelson Arzola; A. Gómez; S. Rincón
Revista Facultad De Ingenieria-universidad De Antioquia | 2013
Gonzalo Rojas; Nelson Arzola
Dyna | 2015
Nelson Arzola; Joyner García