Papers by Keyword: Finite Element Simulation

Abstract: In order to study the pressure carrying capacity of X80 pipe with metal loss defect on the girth weld the water-pressure blasting test of the pipe with metal loss defect was analyzed by experiment and finite element simulation. Based on this, the sensitivity analysis of the factors affecting the pressure carrying of the pipeline, such as the circular size, the axial size, and the depth of the metal loss defect, was carried out. The research results show that the circular size of the metal loss defect on the girth weld had little impact to the pressure carrying capacity of the pipe while it reduced with the increasing of the axial size and the depth of the metal loss defect.

Abstract: Finite Element Method (FEM) becomes one of the most useful techniques to analyze problems in sheet metal forming processes because of this technique can reduce cost and time in die design and trial step [1]. This research was aimed to predict the optimal parameters in order to eliminate cracks and wrinkles on stainless steel sink product under deep drawing named “DLS50”. The material was made from Stainless Steel 304 with thickness 0.6 mm. The parameters that had been investigated were punch angle and velocity as well as pressure of the punch. In order to simplify the process, punch and die in the simulation were assumed to be a rigid body, which neglected the small effect of elastic deformation. The properties of stainless steel sheet was assumed to be anisotropic, behaved according to constitutive equation of power law and deformed elastic-viscoplastic, which followed Barlat 3 components yield function. The deformation for Forming Limit Diagram (FLD) was predicted by the Keeler equation. Most of the defects such as cracks and wrinkles were found during the process on the parts. In the past, practical productions were performed by trial and error, which involved high production cost, long lead time, and wasted materials. From the prediction results, decreasing punch velocity from 50 mm/s to 8.33 mm/s would reduce the blank shearing zone on the corner bottom of the part and remove cracks in the process. The performing of the stainless sink by decreasing pressure in the process from 2.3 bar to 2 bar, and adjusting the punch shape increasing 5 mm. each side would increase formability of sheet metal in all direction, the reduction of cracking tendency zone out of the part. In conclusion by using the simulation technique, the production quality and performance had been improved.

Abstract: A crack is found on the surface of stainless steel casting support. The crack was analyzed by macro and micro observation of fracture surface, Energy Dispersive Spectrometer (EDS) analysis, chemical analysis, microstructure examination and hardness test. Moreover, the stress distribution was simulated by finite element analysis. The results show that the crack model of the support is stress corrosion. The stress at the crack location is the largest. Three main factors of stress corrosion were the crack of paint layer, marine atmospheric environment and the pretightening force for the support. Because the service environment cannot be changed, therefore, surface paint protective effect and reduction of preload can be improved to avoid stress corrosion cracking again on the support.

Abstract: Finite Element Method (FEM) is one of the most popular methods in the automotive industry to reduce problems, time and wastes in production processes. This method can predict the metal forming processes with computer modeling before making forming tools. In sheet metal forming analysis, Forming Limit Diagram (FLD) is one of the most important indicators in FEM, it can tell each forming regions such as cracks, wrinkles and safe zone. However, the FLD that has automatically created in finite element program isn’t enough accurate. Then, the main objective of this research work was to generate FLD of the ultra-high strength steel: NSC980D that usually has been used in auto body frame by using Nakajima's tests. Then, the generated FLD was used to simulate the forming of the automotive parts for solving the cracks caused during the forming along with the Hill’s 1948 material model. The Keeler’s FLD, which is generated automatically by the commercial software applied, was plotted for comparison during simulation, as well. Drawing process of the panel front was investigated by applying FEM simulating tool: PAMSTAMP to analyze the formability and to determine the optimal forming parameters under suitable service conditions. The main parameters of interest were the part and blank configuration. A number of corrections were successively made to successfully form the part. From the analysis of 2 case studies, it was found that tearing was occurred in the first case results. When the forming force was reduced from 15 tons to 9 tons in the second case, the complete forming without tearing and similar like actual forming at the same conditions had been taken place in the second results.

Abstract: In deep hole machining, drilling parameters for twist drills have an important impact on tool life and economic efficiency. In order to explore the influence of drilling parameters on twist drills, this paper established a drilling model for twist drill 45 steel, orthogonal experiments were designed. AdvantEdge FEM finite element software was used to simulate the drilling force, torque and drilling temperature. The drilling force, torque and drilling temperature were analyzed by using the finite element simulation value as the orthogonal experimental value. In order to ensure that the simulation results have certain reference value, the drilling experiment was carried out in order to ensure the simulation results have reference value. Finally, the optimal combination of drilling parameters was obtained.

Abstract: Advanced High-strength steels (AHSS) has widely application in automotive due to their high tensile strength and remarkable ductility. These good mechanical performances are strongly influenced by the processing and final microstructure. This paper performed Deformation Dilatometer and finite element simulation to study the effect of hot rolling parameters such as strain, cooling rate, and holding time at constant temperature on the microstructure formation of Nb-V low carbon microalloyed steel grade. It found that increasing deformation degree increased the volume fraction of ferrite, both of deformation dilatometer and finite element simulation give a similar trend of effects of hot rolling parameters on evolution of volume fraction of ferrite. These results give an insight for industrial application.

Abstract: In view of the particularity of marine foam sandwich composite structure, this paper establishes an equivalent parameter conversion system based on the classical sandwich structure design idea, and forms an equivalent simulation method to determine the initial stiffness, initial failure load and ultimate failure load of the structure. The simulation discriminant method makes the SHELL91 shell unit available for the marine foam sandwich composite structure. The bending test of the basic structure of marine foam sandwich composite beams and plates is described in detail. The equivalent simulation method is verified. The initial stiffness, initial failure load and ultimate failure load of the equivalent simulation are in good agreement with the experimental results. The paper finds through the finite element numerical simulation that the research results are consistent with the reality and have strong practicability and popularization. The paper preliminarily believes that this method can be applied to the simulation calculation of large foam sandwich composite ships and marine structures. The calculation amount is greatly reduced based on ensuring the accuracy, and the calculation work such as strength criterion and stiffness check of the overall structure has Strongly convincing.

Abstract: This paper studies the influence of the strain rate during the superplastic forming on the microstructure evolution of Ti-4Al-3Mo-1V titanium alloy. The finite elements simulation (FES) of the superplastic forming process at a temperature of 875 °C, which considered to be the optimum forming temperature of this alloy, and at a constant uniform gas pressure of 0.4, 0.7, and 1 MPa were performed. The strain rate response across the formed part via FES at each applied gas pressure was analyzed. The superplastic forming using the same forming condition of the FES, applied gas pressure and forming time, was performed via lab forming machine. In initial state before forming, the studied alloy exhibits a mixture of lamellar and equiaxed grain structure. The microstructure evolution after the superplastic forming process for each applied gas pressure was investigated. It was observed that the lamellar microstructure significantly affects the superplastic forming process and the uniformity of the thickness profile after forming.

Abstract: Nowadays, finite element method (FEM) has been widely used to forecast metal forming process, to analysis problems of workpiece, to decrease production cost, and to save time of die design. This work studied the use of FEM as a tool to design a hot forging die for producing an automotive part named Yoke Spline. The part was made from carbon steel grade S45CVL0. There are three processes to produce Yoke Spline, including the buster, rougher, and finisher processes. The objective of the study was to increase efficiency of production by 5%. To achieve this objective, it was necessary to design a new die in the buster process by using FEM to analyze the die size and shape. The new die must produce the workpieces without any defects. The defects regularly found in the forging workpieces are the dimension out of specification, the under filling, and the crack. The sizes of the buster upper die cover are the width and depth. The die width of 44.5, 46.5 and 49.5 millimeters and the die depth of 25, 28 and 31 millimeters were used in the hot forging simulation. From FEM simulation results, it was found that the die width of 46.5 millimeters and the die depth of 28 millimeters were the best to form workpieces without any defects. In summary, the simulation and experimental results were compatible.

Abstract: Erosion wear is the main failure cause of the throttling ring in artillery, which will lead to the reduction of the reliability of the throttling ring, which also will lead to degradation of the performance of recoil brake. According to the working conditions and environmental characteristics of the throttling ring, the finite element model of the erosion wear of the throttling ring is established, and the erosion wear simulation test is carried out to study the erosion wear rules of the throttling ring under different influencing factors, so as to evaluate the reliability of the throttling ring reasonably. It is of great theoretical and practical value to obtain the reliability information of the throttling ring under different working conditions and to ensure the normal performance of the recoil brake.