Papers by Keyword: Parametric Study

Abstract: Heat losses from heating air ducts underground are used in many applications such as heating and air conditioning in cold weather. Researchers worked on heat losses to understand different ways to reduce heat losses to the environment. This project studies a 3-dimensional model of heating rectangular duct in cold surroundings. The model was done numerically. The numerical grid was tested to reach a reasonable approximation and a comparison with correlations from literature showed good agreement. Moreover, parametric study was carried out to study the effect of different parameters on heat losses. These parameters were Inlet velocity V_o, Inlet temperature T_o, outer heat transfer coefficient h_o, and surrounding temperature T_∞. Results showed that higher inlet velocity, inlet temperature, and outer heat transfer coefficient increases the total heat loss to the surroundings while higher surrounding temperature decreases the total heat loss to the surroundings.

Abstract: Sustainable concrete has become more popular due to supplementary cementitious materials (SCMs) that help achieve sustainability. Despite the well-established benefits of these SCMs, the search for substitute materials continues as they become harder to find and adapt to changes with the industry. Concrete performance may be enhanced using bentonite, a commercially available clay mineral that shows promise as an SCM. In the present work, an Artificial Neural Network (ANN) model was developed to predict the compressive strength of cement-based mortar incorporating bentonite as a SCM, by training it on existing data, allowing for better performance and mix design improvement. A comprehensive experimental database comprising test specimens was established. A critical assessment of the collected experimental data suggested that there are several key parameters governing compressive strength gains. The proposed model's parameters, such as weights, biases, and transfer functions, were effectively transformed into a mathematical model that correlates the compressive strength with the key input parameters. An experimental investigation measuring the impact of treating bentonite at various temperatures on compressive strength was also included in the study.The statistical evaluation results indicated that a three-layered Artificial Neural Network model with different hidden neurons could precisely estimate the compressive strength of mortar mixtures modified with bentonite, showing strong agreement with the experimental results. The mortar's compressive strength may be increased by partially replacing cement with calcined bentonite, especially in the initial stages. The type of bentonite and the intended performance determine the appropriate replacement rate and calcination temperature.

Abstract: In this paper, to confirm the effectiveness and validity of the open-source software Salome–Meca, we constructed and operated Salome–Meca in a design/development environment and performed basic problem solving and eigenvalue analysis, as well as structural analysis. A parametric study was then carried out in collaboration with the open-source software Dakota. Analysis results of Salome–Meca matched both theoretical values and analysis results of ANSYS. Furthermore, the parameter research in Dakota confirmed the eigenvalues and deformation behavior of a pump column pipe as each variable in Salome–Meca was changed; moreover, Salome–Meca and Dakota executed a series of analysis operations normally and automatically. Therefore, Salome–Meca and Dakota are expected to optimize the shape of a structure while avoiding resonance points at natural frequencies.

Abstract: The present work is a 3D transient numerical simulation of material flow and heat transfer during the FSW process. The equations of energy, conservation of mass and momentum were solved in the Eulerian coordinate, in which the spatially variable thermo-physical properties and the non-Newtonian viscosity for the flow of material was calculated taking into account the deformation velocity, the temperature and the properties of the material depending on the temperature. In the purpose of calibrating the proposed model, the effects of contact conditions at the tool / work-piece interface such as the friction coefficient and the slip coefficient on thermal cycles, distribution and the evolution of the maximum value of the temperature have been studied. However, the results obtained show a significant asymmetry of the temperature and mass distribution. Convective heat transport was an important heat transfer mechanism near the tool surface. Furthermore, the numerically simulated temperature value, cooling rates and the length of the thermo-mechanically and thermally affected zone increase with increasing slip coefficient.

Abstract: Springback is one of the major defects that continuously concerns the sheet metal experts’ community. It is has long been known that the sheet thickness, the bending angle and the yield stress of the material primarily affect the angle change after the tools’ release. Besides, the consideration of the kinematic hardening (KH) model has powerful influence on the modelling results, too. In this study, we overviewed several possible factors on the springback with finite element modeling of a simple V-die bending operation, highlighting the effect of the material variables on the final shape. AutoForm® R7 software and the built-in theory of kinematic hardening were used for the material characterization, coupled with the Hockett-Sherby isotropic hardening rule as well as the Yld89 yield criterion. The material data for modeling kinematic hardening behavior were obtained by cyclic tension-compression tests, whilst the isotropic hardening and the yield surface parameters were acquired by simple uniaxial tension tests. The simulation results were compared to the experimental springback observations obtained by a CNC bending machine, without using springback compensation. A detailed parametric study was also carried out to highlight the level of criticality of the applied material variables on the final angle change.

Abstract: This paper explores the ultimate strength of the composite floor system of structural steel concrete. ABAQUS, used to research non-linear competencies and ultimate load-carrying capability of such floor systems, developed the Finite Element Model (FEM) in 3-D. A comparison of computed values with experimental results has validated the proposed finite element model. The measured and experimental findings show a good match with an average variation of 10%. In parametric study effects of different sizes of shear studs on the ultimate strength of the floor system have been explored on full size specimens. Results show that an increase in height of the shear stud with the same diameter increases the ultimate strength of the floor system. An Increase in the diameter of the shear stud also increases the ultimate capacity of the floor system.

Abstract: The Philippines is an agricultural country due to its location in the tropics. Because of this nature, the agriculture sector tends to produce a huge amount of waste that if not disposed properly could pose a threat to the society and to the environment. Studies have been performed on the possibilities of incorporating agricultural wastes to various construction materials as a form of waste diversion. In order to address the problem with agricultural wastes as well as to improve the property of construction materials, a study on alkali-treated banana fiber as web reinforcement in concrete was done. In this study, a characterization of alkali-treated banana fiber was done in order to assess the characteristics of a possible reinforcement for concrete by tensile strength test on the fiber. The applicability of the treated fiber was then examined as a web reinforcement in concrete in terms of its load capacity. The parametric study was conducted to investigate the effect on the compressive strength of varying bundle diameter (4 mm, 8 mm, 12 mm, 16 mm) while holding the spacing of mesh at 20 mm and also the effect of varying mesh spacing (10 mm, 15 mm, 20 mm and 25 mm) while holding the diameter at 16 mm. Test results show that the 4 mm diameter of treated banana fiber yielded the highest tensile strength at 314 N compared to only 197 N of the untreated banana fiber. The parametric study results the diameter of banana fiber indicate that the increase in diameter also results in the increase in load capacity. With respect to spacing, the smaller the value of spacing results in higher load capacity.

Abstract: The study of cavitation is of topical interest in both physical and biological sciences. The surface roughness changes the effect of cavitation on a material surface. Due to cavitation, the material with low surface roughness value has relatively more damage, when compared to the one with higher value. In this paper, preliminary numerical studies are carried on cavitation and surface roughness. As a part of the code validation and calibration, the numerically predicted boundary-layer blockage at the Sanal flow choking condition for the channel flow is verified using the closed-form analytical model of V.R. Sanal Kumar et al. (AIP Advances, 8, 025315, 2018) at various surface roughness and found excellent agreement with the exact solution. Parametric analytical studies are carried out for examining the flow features at two different surface roughness and turbulence levels. We noticed that the wavy surface with small waves increases the Nussle number, therefore it is also considered for parametric analysis. Considering the defect-free smooth surface material, we presumed that the cavitation damage in the smooth surface is more than the rough surface because the smooth surface can generate more micro bubbles. These micro bubbles grow into macro bubbles which in turn results in cavitation. This study is a pointer towards for formulating various industrial topics with fluid-structural interaction problems for getting plausible solutions for meeting the needs of various industries.

Abstract: A recent cohesive zone model is applied to the simulation of crack extension in austenitic stainless steel under large scale yielding conditions. The shape of the corresponding exponential traction-separation-relation can be modified in a wide range. In order to investigate the sensitivity regarding the cohesive zone parameters, a systematic parametric study is performed. The shape of the traction-separation envelope has a minor effect on the results compared to the cohesive strength and the work of separation. The aim is to fit experimental data by an appropriate choice of these parameters. Therefore, not only force-displacement curves should be used, but also crack growth resistance curves should be employed. A promising strategy for parameter identification is derived.

Abstract: In different innovative markets, such as electro mobility and flexible electronics, among others, the mechanical joining processes based on sheet metal forming technologies are gaining a significant relevance due to their low cost and ease of automation as compared to traditional joining techniques of riveting, bolting, fastening, welding, etc. In lightweight hybrid constructions, where a high production rate is required, clinching technology demonstrates a sustainable method to join hybrid metal-composite parts. However, the basic mechanisms of this hybrid joining process are not well studied at present and an accepted design theory in this area has not yet been established. The current contribution presents a parametric study of the hybrid clinching joining process. The Taguchi’s design of experiments method is used to investigate the effects of tools’ geometry on hybrid clinching joints’ quality characteristics, i.e. neck thickness, undercut and final bottom thickness. For this purpose, a 2D axisymmetric modelling approach was adopted for its simplicity. The study results are analyzed using the mean response and signal-to-noise ratio approaches. Accordingly, the relevant geometrical parameters of the tools with the highest influence on the accurate shaping of hybrid clinching joints are determined numerically.