FEA-based Simulation Research Articles

Defect prediction and performance optimization of A413 vertical centrifugal castings through FEA-based simulation

This study benefits from advanced simulation based on finite element analysis, where finite element analysis possesses robust numerical algorithms to confront critical industrial challenges, including prediction and optimization techniques. The primary goal is to predict the location and quantity of shrinkage porosity and air entrainment, and to mitigate them by optimizing key casting process factors while considering the geometric effects. Virtual experiments designed through the Taguchi method, with three parameters (aspect ratio, pouring temperature, and mold rotation speed) at five levels each, were conducted using the finite element analysis software ProCAST. Post-experimentation, comprehensive data analyses, including signal-to-noise ratio and response surface methods, were employed to determine optimal conditions. Additionally, a sophisticated regression model was developed to clarify the complex relationship between key parameters and defect aspects. Optimal conditions to reduce shrinkage porosity were identified within parameter ranges of (50–75) rpm, (750–800) °C, and (1.75–2) aspect ratio. Similarly, optimal parameters to reduce air entrainment were identified as 150 rpm, 800 °C, and (1) aspect ratio.

FEA-Based Simulation of Accelerated Ageing in a Power Cable Due to Sustained Partial Discharge Activities in a Spherical Cavity

The reliability of electrical assets is greatly influenced by the quality of their insulations. Key power installations such as power cables are manufactured with polymer-based materials as part of their insulation system. However, accelerated ageing of equipment insulations due to manifestation of defect(s), and partial discharges (PDs) can offset the operation of these systems or even lead to breakdowns. In this study, a non-deterministic model to simulate the phenomenon of repetitive discharges in a spherical air-filled cavity within a practical power cable has been investigated. In addition, the work contributes to the understanding of PD behaviour and field distribution under different ageing conditions considering changes in cavity surface conductivity. First, a section of the practical XLPE cable containing the cavity is developed in 2D using COMSOL software, and a finite element analysis (FEA) of the electric field distribution within the cable insulation is performed. The magnitude of the cavity local field, that is enough to ignite a PD, is investigated. Alongside the COMSOL model, the activity of sustained internal PD is simulated in MATLAB by introducing a random sample generating factor and adjusting the model’s parameters to obtain something close to the practical results. Furthermore, the impact of continuous PD in the power cable under different cavity dimensions and surface conductivity is likewise investigated, and a phase resolved PD (PRPD) pattern is established. The result shows that the magnitude and number of PDs per cycle increase as the cavity size and its surface conductivity increase. Finally, when the cavity surface conductivity rises, the amplitude of the electric field generated by the surface charge distribution and the number of PDs per cycle approach their maximum values.

Image Registration-Based Method for Reconstructing Transcatheter Heart Valve Geometry from Patient-Specific CT Scans.

Accurate reconstruction of transcatheter aortic valve (TAV) geometries and other stented cardiac devices from computed tomography (CT) images is challenging, mainly associated with blooming artifacts caused by the metallic stents. In addition, bioprosthetic leaflets of TAVs are difficult to segment due to the low signal strengths of the tissues. This paper describes a method that exploits the known device geometry and uses an image registration-based reconstruction method to accurately recover the in vivo stent and leaflet geometries from patient-specific CT images. Error analyses have shown that the geometric error of the stent reconstruction is around 0.1mm, lower than 1/3 of the stent width or most of the CT scan resolutions. Moreover, the method only requires a few human inputs and is robust to input biases. The geometry and the residual stress of the leaflets can be subsequently computed using finite element analysis (FEA) with displacement boundary conditions derived from the registration. Finally, the stress distribution in self-expandable stents can be reasonably estimated by an FEA-based simulation. This method can be used in pre-surgical planning for TAV-in-TAV procedures or for in vivo assessment of surgical outcomes from post-procedural CT scans. It can also be used to reconstruct other medical devices such as coronary stents.

Finite Element Simulation of the Flat Crush Behavior of Corrugated Packages

Corrugated paperboards are used for packaging because of their high strength-to-weight ratio, recyclability, and biodegradability. Corrugated paperboard consists of a liner and a corrugated medium and has an orthotropic sandwich structure with unique characteristics for each direction owing to its flute shape. In this study, finite element analysis (FEA) was performed on the flat crush behavior of the corrugated paperboard based on the flute type. The stress-strain (SS) curve and shape change of the flute were analyzed during the flat compression. In addition, it was compared with the FEA results through various experiments. The restraints and boundary conditions applied during FEA were used to properly describe the conditions during the experiment. Specifically, the horizontal translation motion of the top and bottom surfaces of the modeled test specimen was constrained during FEA to correspond to the effect of sandpaper attached to the upper and lower plates of the testing machine. This was done to prevent the specimen from sliding in one direction during the flat crush test. The change in the flute shape of the corrugated paperboard by flute type analyzed through experiments and FEA was very similar; although there was a difference in the absolute value between the two methods of the SS curve, the flute type exhibited a similar trend. Therefore, a qualitative comparative study on the flat crush behavior by flute type was possible with the FEA method, as in this study. Further studies on the material properties of the corrugated paperboard components and the modeling methods of the corrugated paperboard will enable the FEA-based simulation technique to be an alternative tool that can replace the flat crush test.

Structural Assessment of Monocoque Frame Construction using Finite Element Analysis: A Study Case on a Designed Vehicle Chassis referring to Ford GT40

Each vehicle has a different chassis shape and specification, including a sports car. A car must meet several criteria such as comfort, safety, and with a sporty appearance. Before being made, a design process is carried out and analysis is conducted to quantify structural responses, e.g., von-Mises stress test, strain, displacement, reaction force, and safety factor based on the static loads. This research had been produced using an Autodesk Fusion 360 and analysis uses the Finite Element Analysis (FEA). A series of main discussions are directed to examine applied material on the Ford GT40 chassis. After the FEA-based simulation, the maximum displacement is found to be 0,441 mm, von-Mises stress of the chassis is 181.7 MPa with the safety factor 1.14. It indicates that the chassis can hold 548.9 N vertical load still deform elastically and still under allowable material properties. Steel material is suitable for safety and comfort factor of a Ford GT40 sport car.

Investigation and FEA-based simulation of tool wear geometry and metal oxide effect on cutting process variables

In machining, it is clearly noticed that the cutting tool wear influences the cutting process. However, it is difficult with experimental methods to study the effects of tool wear on several machining variables. Thus, in the literature, some earlier studies are performed separately on the effect of tool flank wear and crater wear on cutting process variables (such as cutting forces and temperature). Furthermore when the workpiece material adheres in cutting tool, it affects considerably the heat transfer phenomena. Accordingly, in this work the finite element analysis (FEA) is performed to investigate the influence of combination of tool flank and crater wear on the local or global variables such as cutting forces, tool temperature, chip formation on the one hand and the effects of the oxidized adhesion layer considered as oxide (Fe2O3/Fe3O4/FeO) on the heat transfer in cutting insert on the other hand. In this investigation, an uncoated cutting insert WC–6Co and medium carbon steel grade AISI 1045 are used. The factorial experimental design technique with three parameters (cutting speed Vc, flank wear land VB, crater wear depth KT) is used for the first investigation without adhesion layer. Then, only linear investigation is performed. The analysis has shown the influence of the different configurations of the tool wear geometry on the local or global cutting process variables, mainly on temperature and cutting. The simulation’s results show also, the highly influence of the oxidized adhesion layer (oxide Fe2O3/Fe3O4/FeO) on the heat transfer.

Predict TKA Prosthesis Constraint Behavior Using Simulation—Validation and Applications

Total knee arthroplasty (TKA) prostheses are semi-constrained artificial joints. A prosthesis design should have a level of femorotibial constraint that matches the device's clinical indication. For example, a cruciate retaining (CR) prosthesis is used for patients who have a fully functioning posterior cruciate ligament (PCL), while a CR-constrained (CRC) prosthesis that compensates for PCL function by offering additional anterior stability might be indicated for those who do not.To assess the constraint behavior of a TKA prosthesis, physical testing is usually required, and an industrial test standard has been developed for this purpose (ASTM F1223-08). Finite element analysis (FEA) has been widely used in stress analysis and structural evaluation of various orthopaedic medical devices, but has not been commonly used for joint constraint assessment. This study presents an FEA-based simulation to evaluate the constraint behavior of TKA prostheses. The effectiveness of the methodology was demonstrated by comparing it with results from physical testing, and then the simulation was also used to compare anterior-posterior (AP) constraint behavior of two lines of prostheses (CR and CRC) in the same TKA product family.A CR prosthesis (Optetrak Logic CR, size 3, Exactech) was tested using both simulation and physical testing. The prosthesis system consists of a CoCr femoral component, an UHMWPE tibial insert, and a CoCr tibial baseplate. CAD models assembled at 0 deg of flexion were used. Finite element models were created using 10-node tetrahedral elements, with all materials considered linear elastic. Boundary conditions were set up according to the ASTM F1223 standard (Fig. 1). Nonlinear surface-surface-contact was defined at the femorotibial interface and the insert-baseplate interface. Coefficient of friction was determined from physical testing. The femoral component was driven under a displacement-controlled scheme to slide on the tibial insert. At each time step, constraint force occurring at the articulating surface was derived from the reaction force at the distal fixation. A nonlinear FEA solver (NX Nastran SOL601, Siemens, TX) was used to resolve the simulation. For the physical testing, five prosthesis samples were tested under the same ASTM F1223 setup.AP constraint for two products (CR and CRC) from the same TKA family (Optetrak Logic, Exactech) was evaluated using the simulation method. Three sizes (sizes 1, 3 and 5) from each product line were analyzed to represent the common anotomical range.The simulation successfully captured contact location and pressure along the movement of the femoral component (Fig. 2). The force-displacement curve predicted by the simulation showed a hysteresis loop profile similar to that produced by the physical test (Fig. 3). Taking the curve slope from 0 mm to 5 mm, the simulation predicted 45.7 N/mm anteriorly and 36.4 N/mm posteriorly, which are less than 10% difference from the physical test results (46.4 N/mm anteriorly and 39.6 N/mm posteriorly).The force-displacement curves exhibited hysteresis appearance for both CR and CRC prostheses (Fig. 4). The profile of the curves was generally consistent across different sizes. The anterior constraint of the CRC prosthesis was significantly greater than that of the CR prosthesis, while the posterior constraint was slightly higher. Larger sizes exhibited slightly lower constraint than smaller sizes.This study demonstrated that the simulation was able to closely predict the femorotibial constraint behavior of the TKA prosthesis under ASTM F1223 testing. The simulation results resembled the physical testing results not only in general curve profile but also in the magnitude of slope values. One limitation of the current simulation is that no material nonlinearity was assumed, which could account for some of the difference between simulation and physical test.As an application, the CR and the CRC product lines were compared. The increased constraint of the CRC prosthesis is consistent with its geometrical characteristics and functional intention. The CRC insert is expected to provide significantly greater anterior constraint to prevent paradoxical femoral translation when the patient's PCL is not functioning. The CRC insert is also expected to provide slightly increased posterior constraint due to the elevated posterior lip. The reduced constraint on larger sizes is functionally desired to offer proportional translation freedom. The results demonstrated the effectiveness of the simulation in distinguishing the constraint behavior of different TKA prostheses.A validated simulation method could be very useful in TKA prosthesis design. Because no actual prototypes are required, design evaluation and optimization can be more quickly and easily achieved than using physical testing.

Microstructural Behaviour Study and FEA-Based Fatigue Simulation on Parabolic Leaf Spring

It is compulsory to have a good fatigue life to a component that is heavily subjected to cyclic loading. One of the good examples is parabolic spring, which is one of the components in suspension system for large vehicles. It serves to absorb, store and release back the damping energy due to road irregularity, bump and holes. These activities involve a lot of camber deflection that caused by the tension and compression loads. In reality, the loading that subjected to parabolic spring is variable amplitude loading, but most of the manufacturer used constant amplitude (CA) loading for the fatigue test. The objective of this paper is to relate the simulation result with the microstructure behaviour of the leaf spring that failed due to fatigue. A full scale fatigue test was carried out until that parabolic spring meet failure. In order to investigate the fatigue life, CA signal was generated based on an actual fatigue test on the parabolic spring, and it was then analysed using the FEA-based fatigue simulation. A microstructure study was then performed for both fracture and non-fracture area. From the FEA-based simulation, it gave the prediction on damage that occurred at the critical area and also the prediction on the lowest cycle with respect to the FEA model. In the actual fatigue test, the failure was occurred at the centre part of the spring, which is at bolt join of assembly hole. The microstructure analysis showed that the grain at the fracture area indicated some different from the non-fracture area in term of size, phase and precipitation of carbon.