FEM Simulation Research Articles

Surface slope measurement of steep silicon V-grooves using high NA Linnik interferometry

Abstract Optical topography measurements are of high interest in a lot of industrial
and academic fields. One of the most common associated measurement methods
is coherence scanning interferometry, but even though it provides sub-nanometer
axial resolution, its lateral resolution is diffraction limited. Not only the feature
size is a limiting factor for optical measurements, but also steep surface slopes
may lead to problems, since the acceptance angle of the objective lens limits the
maximum surface slope angles that can be measured. Here we use a Linnik-type
interferometer with objective lenses of numerical apertures of 0.95 in order to
maximize the measurable surface slope angle. We demonstrate that silicon V-groove structures with a slope angle of 54.74° can be measured. We compare the directly measured surface slope angle with an angle calculated from light that is reflected two times by the V-grooves. To verify our measurement we compare the measurement results to rigorous FEM simulations.

High‐velocity impact response and damage behavior of bio‐inspired helicoidal composite laminates: Experimental and numerical investigation

AbstractBio‐inspired helicoidal composite laminates have been found to have better impact resistance and energy absorption than conventional laminates. To study the impact responses and damage behaviors of bio‐inspired helicoidal composite laminates under high‐velocity impact, the composite laminates with three helix angles were designed and tested. Two types of light‐gas gun were used to provide low and high impact energies, the velocity was measured using a velocimeter and the damage to the laminate profile was observed by scanning electron microscopy. Numerical simulation is then used to simulate the damage behavior of the helicoidal laminates based on the Hashin failure criterion and the revised dynamic increase factor. The results show that: under an impact of low energies, the helicoidal mechanism serves to absorb the impact energy through the generation of additional delamination. The laminates with the helix angle of 15° exhibits the maximum delamination area and the minimum residual velocity. However, under the impact of higher energies, the helicoidal mechanism is unlikely to improve the energy absorption and will inhibit the delamination damage. The laminates with the helix angle of 45° have the greatest inhibitory effects on delamination damage, with a delamination area reduction of 35.41%. Due to these differences, therefore, the use of helicoidal laminates should be more cautious in high‐velocity impact resistance and better avoid high‐energy situations. These findings can support the design of novel impact resistance structures.Highlights High‐velocity impact tests and FEM simulation of helicoidal laminates are carried out Damage behaviors and failure mechanism of helicoidal laminates are studied Delamination and fiber breakage are the main failure modes The laminates with the helix angle of 15° has the best impact resistance.

Development tests and FEM simulations of maximum load characteristics of medium voltage fuse links

Development tests and FEM simulations of maximum load characteristics of medium voltage fuse links

Fatigue-Limit Assessment via Infrared Thermography for a High-Strength Steel.

Infrared thermography techniques have proven to be very effective for assessing the fatigue limits of metallic materials with obvious temperature variations. But for some materials, it has been shown that the temperature variation is very limited, and the accuracy of infrared thermographic techniques is not verified. In this study, the fatigue properties of a high-strength steel (SAE52100) were evaluated with traditional fatigue-loading techniques and infrared thermographic methods. The traditional fatigue experiments were loaded at a frequency of 80 Hz with a stress ratio of R = -1, and the fatigue limit at the fatigue lifetime of N = 107 cycles was about 800 MPa. Besides, three additional specimens were loaded with step-by-step increasing stress-loading amplitude, where the maximum temperature increments and temperature distribution were recorded via infrared thermographic techniques. The infrared detections revealed that the maximum value of the temperature increase was only about 1 °C. The fatigue limit was first evaluated based on the maximum temperature variation, then the prediction was refined based on fatigue intrinsic dissipation. The fatigue limits predicted with maximum temperature variation were shown to be 841 MPa, 772 MPa, and 787 MPa, respectively, while the fatigue limits predicted based on fatigue intrinsic dissipation were 793 MPa, 791 MPa, and 789 MPa. Finally, an FEM simulation of temperature variation during fatigue loading was implemented to verify the experimental results. This study provides a solid foundation for the applications of infrared thermography techniques for materials with lower energy dissipations.

PARAMETRIC DESIGN AND ADAPTIVE SIZING OF LATTICE STRUCTURES FOR 3D ADDITIVE MANUFACTURING

The present research is developed into the realm of industrial design engineering and additive manufacturing by introducing a parametric design model and adaptive mechanical analysis for a new lattice structure, with a focus on 3D additive manufacturing of complex parts. Focusing on the land-scape of complex parts additive manufacturing, this research proposes geometric parameterization, mechanical adaptive sizing, and numerical validation of a novel lattice structure to optimize the final printed part volume and mass, as well as its structural rigidity. The topology of the lattice structures exhibited pyramidal geometry. Complete parameterization of the lattice structure ensures that the known geometric parameters adjust to defined restrictions, enabling dynamic adaptability based on its load states and boundary conditions, thereby enhancing its mechanical performance. The core methodology integrates analytical automation with mechanical analysis by employing a model based in two-dimensional beam elements. The dimensioning of the lattice structure is analyzed using rigidity models of its sub-elements, providing an evaluation of its global structural behavior after applying the superposition principle. Numerical validation was performed to validate the proposed analytical model. This step ensures that the analytical model defined for dimensioning the lattice structure adjusts to its real mechanical behavior and allows its validation. The present manuscript aims to advance additive manufacturing methodologies by offering a systematic and adaptive approach to lattice structure design. Parametric and adaptive techniques foster new industrial design engineering methods, enabling the dynamic tailoring of lattice structures to meet their mechanical demands and enhance their overall efficiency and performance. Keywords: Computer-Aided Design, Industrial Design, Innovative Design, Additive Manufacturing, FEM Simulations

Structural optimization and magneto-thermal coupling simulation of limited angle torque motor

The limited-angle torque motor (LATM) is an electric actuator capable of rotating within a limited angular range and outputting a stable torque. It features a simple structure and high reliability and can be used in precise position or torque control scenarios. To reduce the torque fluctuation within the constant torque range (CTR), the effects of the stator tooth topology and size, PM magnetization direction and size, and sleeve permeability on the torque-angle characteristic of the LATM within the CTR were analyzed through FEM simulation, and the characteristics of the LATM before and after optimization were compared. Furthermore, a magneto-thermal coupling simulation of the steady-state temperature increase and thermal deformation generated by the LATM was conducted to study the effect of temperature on the LATM. The results show that the optimized LATM can output a more stable torque within the CTR and that the rated torque fluctuation rate relative to the torque at the zero position decreases by 3.2%. In addition, the temperature increase and corresponding thermal deformation of the optimized motor at 20 °C decreased by 0.22% and 0.29%, respectively.

Enhancing the Accuracy in Predicting the Maximum Bearing Capacity of Bored Piles Using Derivative Analysis and FEM Simulation

Enhancing the Accuracy in Predicting the Maximum Bearing Capacity of Bored Piles Using Derivative Analysis and FEM Simulation

Superior mechanical properties of an additively manufactured gradient lattice structure through FEM simulation and in-situ compression tests

Currently, the increasing incidence of bone defects and damage due to diseases and trauma, the treatment of bone defects usually uses autologous bone graft or allogeneic bone graft, however, the amount of autologous bone is limited, and there is also the risk of infection at the site of bone extraction, and allogeneic bone graft also faces problems such as disease transmission and immune rejection. In summary, artificial bone provides a new option for patients. This study investigates the mechanical properties of homogeneous and gradient Gyroid and Diamond porous structures, designed with average porosities of 50%, 60%, and 70%, using triply-periodic minimal surface models for artificial joints. Finite Element Method simulations and compression tests were employed to characterize the mechanical properties of Ti6Al4V porous scaffolds fabricated using the selective laser melting technique. The measured elastic modulus of the scaffolds ranged from 6.24 to 10.5GPa, meeting the requirements for orthopedic implants. Gyroid structures were shown to exhibit superior nominal stiffness compared to Diamond structures at equivalent porosity levels. Furthermore, the linear gradient porous structures demonstrated significantly higher elastic modulus, yield strength, and compressive strength compared to homogeneous porous structures, with increases of 66.9%, 20.3%, and 16.5%, respectively. The energy absorption capacity of the linear gradient porous structure was also found to be 3.3-fold greater than that of the homogeneous structure.The lightweight design of this linear gradient porous structure provides the basis for bone implants for biomedical applications.

REVERSE ENGINEERING OF THE METAL SPINNING PROCESS FOR CONICAL ANGLE 163° USING FEM WITH SIMUFACT FORMING

The process of metal spinning is performed based on years of experience and empirical research. For workpieces with complex shapes, this is a problematic and time-consuming task. The use of numerical studies is intended to ease the design of the metal spinning process. This article presents the results of shaping a conical product with an angle of 163° for two materials: AA 1050A and DC04 steel. The work under laboratory conditions was carried out using the MWS 200 machine. FEM simulations were performed in the Simufact Forming program. The testing methodology consisted of 4 consecutive stages. First, the spinning process was carried out with AA 1050A material. Second, boundary conditions were selected for FEM simulation. The third, spinning FEM tests were performed for DC04 steel. The fourth, metal spinning process tests were performed with DC04 steel. The influence of selected process parameters on the obtained product and the correlation with FEM studies are described. The results obtained showed that the discrepancy between laboratory and numerical tests is dependent on the material tested and its mechanical properties. In the case of aluminum, which is easier to form, it was possible to use an identical trajectory of the forming roll with an accuracy of 2.25%. As the mechanical parameters of the material increase, the differences between laboratory and numerical results increase. Consequently, a gap correction was necessary to achieve convergence. The value of the trajectory correction was determined by comparing the laboratory results obtained with the numerical results. The introduction of the correction resulted in a convergence between FEM and laboratory tests of 2.06%.

FEM simulation of breast deformation with semi-fluid representation.

In image-guided surgery for breast cancer, the representation of the breast deformation between planning and surgery plays a key role. The breast deforms significantly and behaves as a fluid with some constraints. Concretely, the deep fat layer in the breast deforms fluidly due to its incomplete fixation to the chest wall, while the anchoring structures by fascia avoid excessive deformation. In this study, we propose a method to simulate the semi-fluid deformation of the breast, considering the fluidic properties of the adipose tissue under the constraints of the anchoring structures. The proposed method prioritizes anatomical features of the breast, enhancing tissue mobility near the chest wall and modeling the anchoring structure of the fascia along the inframammary fold. To simulate semi-fluid deformation, constraint force from anchoring structure is applied to prone-positioned breast model, using a finite element method. The results of the evaluation indicate a tumor center registration error of 11.87 ± 4.05mm. Additionally, we verified how semi-fluid representation affects the registration error. The tumor's Hausdorff distance decreased from 12.89 ± 6.24mm to 11.50 ± 4.38mm with considering semi-fluidity. The results showed that the use of semi-fluid representation tends to reduce registration errors. Therefore, it was suggested that the proposed method could improve the accuracy of breast posture conversion.

FEM Simulation of Rolling-Pressing Process with Horizontal and Vertical Rolls

FEM Simulation of Rolling-Pressing Process with Horizontal and Vertical Rolls

Dynamic characteristics of micro-perforated complex beam structures

This paper discusses research concerning the fluctuating dynamic characteristics of various micro-beams featuring intricate designs and perforated surfaces across their entire operational faces. The complex beam structures consist of different types: folded beam, V-shaped beam, and crab-shaped beam with different boundary conditions: fixed-free, fixed-fixed for the simple single beam, and fixed-guided for the rest. The types of holes on the body of the beams are choice in square and circle-shaped for common. In addition, the methodology to determine the dynamic characteristics of the perforated beam is also proposed based on using FEM simulation software. The results show that the dynamic characteristics of the beam in which the holes are distributed depend on the size and shape of perforated holes. As the size or quantity of holes on the surface of the beam in perforated micro-beams grows, the equivalent stiffness drops noticeably. Consequently, the fundamental frequencies of the MEMS systems that include these micro-beams also diminish. The damping coefficient also reduces thanks to the occurrence of these holes. The maximum decrease in damping coefficient reaches 84% in the ideal case for the crab-shaped beam with square holes. These results can be used to optimize the MEMS structures in future research.

Volumetric mix-design modification and vibration attenuation analysis of rubberised epoxy asphalt track for railway

Rubberized asphalt mixture effectively reduces vibrations in railway track due to the elasticity of crumb rubber (CR) and the viscoelasticity of asphalt binder. This study aims to design a rubberized epoxy asphalt mixture using the modified volumetric mix-design method named the multi-point supported skeleton for asphalt mixtures (V-S method). The feasibility and vibration attenuation of the precast epoxy asphalt track was evaluated through a 3D FEM simulation at a 350 km/h speed. By combining the V-S method with the equivalent volume replacement principle between CR and coarse aggregate, four types of rubberized epoxy asphalt mixtures were proposed using the dry method. Indoor test results confirm that these mixtures meet the required specifications. The FEM results demonstrate that the designed epoxy asphalt track meets the design criteria and the components of the EA-4CR track structure demonstrate superior vibration reduction performance among the cases with the same increment in CR content.

A novel hybrid method for predicting maglev train-induced environmental vibrations combining field measurement, 2.5D FEM modelling and multi-objective optimization

The maglev system has been developed rapidly in recently years since its advantage in mass transportation, ride comfort and energy efficiency, which also caused an increasing concern on the maglev train-induced environmental vibrations. This paper presents a novel hybrid framework for predicting high-speed maglev train-induced environmental vibrations combining field measurement, 2.5D FEM simulation and multi-objective optimization. First, a maglev train-guideway-soil coupled model considering guideway irregularities was proposed to calculate the ground vibration using 2.5D FEM. Then, the guideway irregularity spectrum and soil damping are inverted by the optimization process using the NSGA3 genetic algorithm, in which the differences of measured and calculated vertical vibrations of measuring points are chosen as objective functions. With the inverted guideway irregularity spectrum and soil damping, the ground vibrations were calculated using the 2.5D FEM model and compared with the field measurements. It was found that the inverted PSD spectrum of guideway irregularity generally decreases as the spatial frequency increases, exhibiting a similar trend as the measured ones. The results obtained by the proposed hybrid prediction method agree well with the field measurement in both time domain and frequency domain. The prediction error for the vertical vibration level of all measuring points induced by five maglev train passing are mainly less than 10 %, indicating that the proposed hybrid method provided a reliable and effective method for vibration prediction combining field measurement and numerical simulation.

Deep Rolling Process Modeling Using Finite Element Analysis in Residual Stress Measurement on Rail Head UIC860 Surface

This study investigates the effects of deep rolling parameters, pressure, speed, and offset, on the residual stress distribution and material deformation in UIC 860 Grade 900A railway rails. We will model deep rolling to simulate the process and predict the residual stress profile in railway rails. Subsequently, we will rigorously compare and analyze the FEM simulation results with experimental data to optimize deep rolling parameters for improved residual stress distribution. Using both experimental methods and finite element analysis via ANSYS 2023 R1, the study varied deep rolling parameters. Experimental deep rolling pressure was set at 150 bar, speed at 1800 mm/min, and offset at 0.1 mm, while FEA simulations predicted corresponding pressures of 157 bar and speed of 1796.52 mm/min. These parameter settings were chosen to induce significant surface compressive stresses that could enhance the material’s mechanical performance. The experimental results showed an average compressive residual stress of 498.9 MPa, closely aligning with the FEA-predicted value of 502.5 MPa. A paired t-test revealed no statistically significant difference between the two results, with a T-value of −0.22 and a p-value of 0.833, validating the reliability of the FEA model. The consistent deformation observed in both experimental and FEA simulations, especially with a 0.1 mm offset, confirmed that the rolling parameters were effective in producing uniform stress distribution, albeit with a slightly extended processing time due to the small offset. Overall, the findings confirm that optimizing the deep rolling parameters of pressure, speed, and offset leads to favorable residual stress distributions and improved material properties. The results indicate that FEA is a reliable tool for predicting the outcomes of deep rolling, and this study provides a strong foundation for further refinement of the process to enhance performance in practical applications, such as railway rail treatments.

A hybrid FEM-Kriging approach for fatigue assessment of a steel pipe riser from field-measured motions

The establishment of monitoring systems for Floating Production Units motions provides an important input needed for real-time assessment of riser fatigue through Finite Element Method analysis. Standard practice relies on these simulations to obtain the loads required to calculate fatigue life along the riser, however, it is a CPU-intensive approach which makes it difficult to achieve results in real-time. Since interest often lies on few critical points on the riser, such as 1st weld and TDP, the number of outputs of is vastly reduced, making surrogate models an interesting and cost-effective alternative. Previous work such as DAMASCENO (2020) has shown Kriging to be a good choice for time series prediction, yielding adherent results for outputs such as forces and moments by having vessel motions as inputs. This method requires a short FEM simulation (~600 s) to train the models that will expand the output time-series to full 3,600 s duration, which will be shown to be far less CPU intensive. A case study for a SCR connected to a semi-submersible platform is presented, evaluating fatigue life from 5715 hours’ worth of data from the year of 2018 through both methods. Analysis of the obtained results yields additional tools which correlate damage to vessel motions, which are then used to prioritize sea states and evaluate the most cost-effective FEM and Kriging combination.

Application of the damping bag on supersonic rocket sled tests

Abstract In recent years, ground-based ultra-high-speed systems such as high-speed rocket sled and super-high-speed railways have become a research hotspot, especially the rocket sled which can currently exceed March 8 in top speed. However, due to the non-perfect smoothness of the slide and the complex aerodynamic environment, the rocket sled has a serious impact on the test articles or test instruments on the rocket sled. Therefore, it is necessary to use vibration isolation facilities to reduce the vibration on the rocket sled. In this work, a vibration damper based on the 4 damping bags with high efficiency damping effect for high-frequency vibration is design. The FEM simulation, vibration table experiments and a supersonic rocket sled test are design to demonstrate the attenuation effect of the vibration damper. All results show the vibration damper can isolate elastic waves in the frequency range from 400 Hz to 2000 Hz.

Analysis of numerical calculation methods for oblique penetration of projectiles into concrete targets

Abstract This article uses finite element software ANSYS/LS-DYNA to analyze the numerical simulation method of projectile oblique penetration into concrete targets. FEM method is commonly used for numerical simulation of projectile penetration into concrete targets, but there is a problem of large deformation of concrete when penetrating concrete targets obliquely, and FEM method is prone to mesh distortion. Based on the experimental results of oblique penetration of the projectile into concrete, this article uses FEM, SPH, and FEM-SPH numerical simulation methods to obtain the numerical simulation results of oblique penetration into concrete targets at different velocities and incident angles of the projectile. The results from the deflection angle of the projectile and the depth of the crater indicate that compared with using FEM and SPH methods separately, FEM-SPH method has higher consistency with experimental results in simulating the oblique penetration of the projectile into concrete.

Study to localize isometric points of anterior band of inferior glenohumeral ligament and to use long head of biceps as a graft: A finite element analysis and arthroscopic cadaveric demonstration

BackgroundThe inferior glenohumeral ligament (IGHL) comprising the anterior and posterior bands with interposing axillary pouch is an important static stabilizer of anterior translation and external rotation (ER) in the 90-degree abduction position. No literature is available to determine any ideal graft or isometric point for fixation of any graft to replace the functionality of IGHL such that the tensile stress acting on the graft is under the limits of the tensile properties of the graft used for reconstruction. MethodsUsing finite element method analysis (FEM) of the long head of the biceps tendon (LHBT) with modeling and simulation process, the ultimate tensile strength of the LHBT at the different clock positions of the humeral head attachment and angular positions of the humerus were determined through a combination of Taguchi Design of Experiments and simulation using ANSYS (Analysis system) software. ResultsThrough FEM simulations using the ANSYS software, it was concluded that the clock position of 7:30 would be appropriate to fix the biceps Tendon on the humerus. The tensile stress induced in the IGHL at 7:30 on the humerus, at 90° abduction with 90° rotation of the humerus, as well as at 120° abduction with 90° rotation of the humerus was evaluated and validated. ConclusionsReconstruction of anterior band of IGHL using LHBT in its isometric points found in this study can provide a solution to manage anterior instability anatomically rather than non-anatomical procedures like dynamic anterior stabilization. This will be an anatomical procedure that will bridge the gap between anatomical Bankarts procedure and non-anatomical latarjet procedure. The LHBT can be suitable graft material for the anterior band of the IGHL reconstruction. Our study demonstrated that the most optimal fixation points for the graft, which resulted in the least tensile stress on the LHBT, were found to be at the 3 o'clock position on the glenoid and the 7:30 o'clock position on the humerus. Level of evidenceLEVEL 5 – methodological verification and validation.

Multi-Resolution Real-Time Deep Pose-Space Deformation

We present a hard-real-time multi-resolution mesh shape deformation technique for skeleton-driven soft-body characters. Producing mesh deformations at multiple levels of detail is very important in many applications in computer graphics. Our work targets applications where the multi-resolution shapes must be generated at fast speeds ("hard-real-time", e.g., a few milliseconds at most and preferably under 1 millisecond), as commonly needed in computer games, virtual reality and Metaverse applications. We assume that the character mesh is driven by a skeleton, and that high-quality character shapes are available in a set of training poses originating from a high-quality (slow) rig such as volumetric FEM simulation. Our method combines multi-resolution analysis, mesh partition of unity, and neural networks, to learn the pre-skinning shape deformations in an arbitrary character pose. Combined with linear blend skinning, this makes it possible to reconstruct the training shapes, as well as interpolate and extrapolate them. Crucially, we simultaneously achieve this at hard real-time rates and at multiple mesh resolution levels. Our technique makes it possible to trade deformation quality for memory and computation speed, to accommodate the strict requirements of modern real-time systems. Furthermore, we propose memory layout and code improvements to boost computation speeds. Previous methods for realtime approximations of quality shape deformations did not focus on hard real-time, or did not investigate the multi-resolution aspect of the problem. Compared to a "naive" approach of separately processing each hierarchical level of detail, our method offers a substantial memory reduction as well as computational speedups. It also makes it possible to construct the shape progressively level by level and interrupt the computation at any time, enabling graceful degradation of the deformation detail. We demonstrate our technique on several examples, including a stylized human character, human hands, and an inverse-kinematics-driven quadruped animal.