Papers by Keyword: Temperature Distribution

Abstract: Carbon fiber reinforced thermoplastic (CFRTP), such as carbon fiber reinforced polyetheretherketone (CF/PEEK), are applied in aerospace structures because of their high specific strength and recyclability. In this study, cutting tests were conducted to investigate cutting force in drilling of CF/PEEK composites. The lower cutting force was measured at the higher spindle speed. Temperature distributions on the exit side of the hole were compared between two spindle speeds, the temperature at high spindle speed indicates a higher value. The different conditions on machined hole walls were observed between the two spindle speeds. Then, an energy based force model was applied to analyze the thrust and torque during drilling, in which the cutting edge was discretized, and the chip flow was determined to minimize cutting energy. Based on the predicted shear and friction works, a finite difference thermal analysis was performed to evaluate temperature distributions in the tool, chip, and workpiece. The analysis indicated that higher spindle speed leads to an increase in cutting temperature. The results suggest that temperature-dependent behavior of the thermoplastic matrix may influence the shear stress on the shear plane and thereby contribute to the reduction in cutting force at the higher spindle speed.

Abstract: Selective Laser Melting (SLM) is a promising technique for fabricating intricate metal components. The scanning strategy is a critical parameter that can be optimized to improve the quality of the final parts, as different strategies produce temperature distribution variations. It can impact on the melt pool dynamics and the mechanical properties of the fabricated components. In this study, four scanning strategies were investigated: uni-directional scanning, altered-sequence uni-directional scanning, bi-directional scanning, and altered-sequence bi-directional scanning. Their effects on localized temperature distribution, melt pool morphology, and surface roughness (Ra) during the SLM process of Ti-6Al-4V across five tracks were evaluated using numerical simulation. The simulations were performed using FLOW-3D AM. This simulation integrates the Discrete Element Method (DEM) with Computational Fluid Dynamics (CFD) model. The simulation results demonstrated that the scanning sequence and scanning direction directly effects on the localized temperature distribution. Heat accumulation is more diffusely distributed over the last three scanned tracks in bi-directional scanning and altered sequences of bi-directional scanning. The scanning sequence significantly affects melt pool depth. A symmetric depth profiles of the five tracks were formed at altered sequences of uni-directional scanning and altered sequences of bi-directional scanning cases. Conversely, the left-skewed profiles, where melt pool depth gradually increases with each additional track, peaking at the last one, were generated at uni-directional scanning and bi-directional scanning cases. This trend is primarily attributed to heat accumulation from preceding solidified tracks. In addition, both scanning direction and scanning sequence are significantly impact on the surface roughness by changing from uni-directional scanning to bi-directional scanning showed 27.38% of Ra reduction and changing from uni-directional scanning to altered sequences of uni-directional showed 14.29% of Ra reduction.

Abstract: The purpose of this study is to evaluate the accuracy of a simulation model for the Rotary Friction Welding (RFW) process of AA6061 aluminum alloy. RFW, widely used in the aerospace and automotive industries, is known for producing strong welds with minimal heat-affected zones (HAZ). Using ABAQUS software, a numerical model was developed to simulate key aspects of the process, such as heat generation, material flow, and axial shortening. The simulation results were compared with experimental data and previous studies to validate the model’s accuracy. The comparison demonstrated the model’s ability to closely replicate reality welding conditions, making it a reliable tool for optimizing welding parameters and improving the RFW process for AA6061.

Abstract: Nowadays, microwelding processes have been developed for various technologies, mainly for electronic applications. Resistive bonding is usually used, but electrical energy consumption represents a challenge due to energy crisis in terms of lack of energy supply and prices. This paper aims to evaluate the carbon footprint and economic issues related to microwave welding of aluminum plates against conventional resistive bonding. The research performed has shown that for different levels of microwave injected power from 600 up to 1200 W, the calculated footprint based on energy consumption has shown the sustainability of the microwave welding process. The total energy consumed for microwelding process was less than 360 Wh meaning a total cost up 0,2 euro/100 joints.

Abstract: In this article, we aim to investigate the effect of pipe thickness on the deformation of welded joints in tubular structures. To this end, pipes with a diameter of 60 mm and a length of 215 mm will be utilized in both simulation and experimental processes. The Tungsten Inert Gas (TIG) welding method, known for its high-quality welds, will be employed to join the two steel pipes. The study will be conducted with four different pipe thicknesses: 2.5 mm, 3.2 mm, 4.0 mm, and 5.2 mm, to cover a wide range of thicknesses commonly used in industrial applications. In addition, to validate the accuracy of the simulation method, experimental tests will be carried out for selected simulated cases. The results of the study indicate that structures with thinner pipe walls exhibit higher residual temperatures and stresses, which leads to more deformation. Therefore, it is crucial to consider the pipe thickness when designing and welding tubular structures. After comparing the deformation results obtained from both simulation and experimental tests, we conclude that the simulation method is an effective tool for predicting the deformation of welded joints in tubular structures. By utilizing simulation methods, engineers can optimize the welding parameters and select the appropriate pipe thickness to minimize deformation and ensure the structural integrity of tubular structures.

Abstract: During selective laser sintering (SLS) process, the laser transmission in the polymer powder bed and solid polymer is different. The laser interaction with the powder bed splits into absorption, reflection and scattering three parts. The photon scattering between the polymer particles leads laser repeated absorption by particles, changes the photon’s traveling directions, and further influences the temperature distribution at the scanning laser area. New distribution and attenuation coefficients need to be introduced for correcting the results. For better simulating the photons travel ways, we introduce the modified Monte-Carlo method and Mie-Scattering theory to predict laser distribution in the polymer powder bed, by considering the scattering phenomenon. This paper analyses how the initial porosity influences the maximum temperature, laser attenuation rate and porosity change rate. The results show that lower porosity promoting the laser scattering phenomenon, decreasing the maximum temperature and the powder porosity change rate.

Abstract: The existing means for calculating the fire resistance of steel reinforced concrete horizontal structures beyond the fire resistance limit for more than two hours have been studied. There were conducted the computational experiments on the analysis of thermal load in case of fire for up to 3 hours, without taking into account the mechanical load on steel reinforced concrete slabs, modeled using steel sheets. The indicators obtained as a result of thermal computational experiments provide an opportunity to analyze the temperature distribution in the thickness of steel reinforced concrete horizontal structures made with a steel sheet. The relevant results can be used to determine the indicators of fire resistance of these structures for at least 3 hours. Thus, the thermal dependences, studied in this work, are a scientific basis for improving the capabilities of existing methods for determining the fire resistance of steel reinforced concrete horizontal structures with a steel sheet. The process of determining the temperature distribution indicators in these structures was performed using the standard method for solving the equations of thermal conductivity using the finite element method. Based on the results of solving the thermal problem, the graphs of thermal dependences were constructed, providing an opportunity to further analyze the indicators of fire resistance on the basis of the onset of signs of loss of load-bearing and insulating capacity. In order to perform computational experiments, the necessary calculation models were built that take into account the thermal effect on the studied structures under the standard temperature mode of fire.

Abstract: Modeling of the temperature distribution during electric arc surfacing with a strip electrode is carried out in relation to the design scheme of a semi-infinite body. Also, in the work, the temperature distribution was calculated when a flat layer was heated by a linear source, which made it possible to compare the temperature distribution data without and taking into account the heat release conditions at the product boundaries. The simulation results showed that the control of heat input into the base metal when using mechanical control actions makes it possible to reduce the overheating of the weld pool, reduce the area of the melting isotherm, and reduce the cooling rate of the heat-affected zone. By calculation, the previously determined optimal range of values of the frequency of control actions of 40÷60 Hz was confirmed, which makes it possible to ensure the minimum depth of penetration of the base metal and obtain a favorable structure in the heat-affected zone, prone to the formation of a coarse-grained structure.

Abstract: Friction stir spot welding process is a solid state joining process which has attracted great attention due to its ability to join low melting point light weight alloys such as aluminium and magnesium with high efficiency. In order to understand the complex thermo-mechanical joining process involved with friction stir spot welding, a numerical simulation study was done using ABAQUS finite element software. The simulation primarily aims to interpret the effect of a set of process parameters and tool geometry on the workpiece plates. Johnson-Cook damage criteria model was used to obtain the stress and strain distribution on the workpiece consisting of aluminium 6061 and magnesium AZ-31B placed in a lap configuration. Temperature distribution of the workpiece was obtained by simulating a penalty based frictional contact between the tool and the plate. The thermal results showed that the maximum temperatures attained were significantly lower than the melting points of the base materials indicating that the material mixing and joining occurred as a result of superplastic deformation process instead of melting. Change in material flow behaviour was also observed by the model as pin and shoulder geometries changed.

Abstract: Prepreg manufacturing process is one of the most important preparatory technological processes, quality of which has the decisive influence on the physical, mechanical, processing and operational characteristics of the finished composite product. However, manufacturing of prepregs is associated with a number of harmful factors, negatively affecting the participants in the technological process and the environment. Consequently, significant additional costs are required in order to ensure specified maximum permissible levels and concentrations of the harmful products released by the components of polymeric composite materials in the product manufacturing process. The paper deals with the study of peculiarities and efficiency of impregnation of the heated reinforcing material using solvent-free binder. The method for predicting the optimal process parameters of binder solutions for impregnation of prepregs, taking into account the safety of production activity, has been developed. The problem of thermal conductivity from the heated reinforcing material to the binder, which allowed establishing the law of temperature distribution over the depth of the impregnating bath, depending on the duration of continuous impregnation, has been solved. It is found that the binder, with the duration of impregnation even within one working shift, heats up to the temperatures excluding the formation of centers of exothermic polymerization reaction in it. It indicates the availability of the effective regimes of impregnation using the method under study. The paper proposes the practical ways of improvement of the investigated method of impregnation by varying the wavelength, programmed change of the temperature of the reinforcing material at the entry to the bath, and setting of the optimal coordinates of the binder supply as it is drawn in the process of continuous impregnation of the reinforcing material.