Linear Static Finite Element Research Articles

Optimal mechanical properties of Hydroxyapatite gradient Voronoi porous scaffolds for bone applications — A numerical study

Irregular Voronoi-based lattice (IVL) structures in tissue engineering (TE) have significant potential for bone regeneration. These scaffolds can mimic natural human bone interconnectivity by gradually altering strut thickness (ST) and seed point space (PS), which affects both mechanical and biological characteristics. This paper investigates the impact of design parameters, ST and PS, on Hydroxyapatite (HA) ILV structures’ mechanical properties (elastic modulus (E) and maximum compressive strength (MCS)) and geometrical characteristics (pore number, size, and distribution, surface area (SA), and surface area-to-volume ratio (SA/VR)). Four types of IVL scaffolds were designed; PC-TC (Constant PS-Constant ST), PC-TG (Constant PS-Gradient ST), PG-TC (Gradient PS-Constant ST), and PG-TG (Gradient PS-Gradient ST). The study, conducted through linear static structural finite element analysis (FEA) with maximum stress criteria, underscores the profound impact of irregularity and morphology on mechanical performance and geometrical features. Regarding SA and SA/VR, a comparison between PC-TC with other proposed scaffolds showed a minor improvement for PC-TG, while higher significant improvements were found for both PG-TG and PG-TC. In terms of pores distribution and number, no noticeable improvement was observed for the PC-TG scaffold compared to PC-TC. In contrast, PG-TC and PG-TG lattices demonstrated a variety of pore distributions and approximately doubled pore numbers. Studying mechanical properties, considering E and MCS, showcases substantial gains for PG-TC. It, however, revealed that for the rest of the scaffolds, no enhancement was observed regarding E. Based on these results, gradient PS proved to be more effective than gradient ST in enhancing mechanical performance and geometrical properties. Due to these improvements, this study holds promise for expediting bone regeneration and reducing postoperative complications in bone replacement applications.

Protective potential of different mouthguard thicknesses against perianaesthetic dental trauma: a patient specific-finite element study

Perianaesthetic dental trauma is a common anaesthesia-related complication. Theprevious studies have shown a lack of knowledge regarding mouthguard usage and controversial results related to perianaesthetic dental trauma prevention. This study aimed to conduct a finite element analysis of the compressive and tensile stresses on the tooth-periodontal ligament-bone complex using custom-made mouthguards of different thicknesses and glass fibre splints to prevent perianaesthetic dental trauma. Custom-fitted ethylene-vinyl acetate mouthguards of two different thicknesses (2 and 3 mm) and glass fibre splint were modelled. A linear static finite element analysis was performed by applying a rigid Macintosh laryngoscope to the palatal surface of the maxillary central incisors at 150 N. The model without a mouthguard and glass fibre splint showed the highest stress values at the palatinal root surfaces during the impact. Increasing the mouthguard thickness significantly decreased the stress-strain values regardless of the presence of the glass fibre splint. Maximum stresses in the group using the 3 mm mouthguard were the lowest compared with the other groups.

Failure analysis of the collapse of a raised steel wine tank

As structural damage or even catastrophic collapses are sometimes due to improper design, underestimated design loads or unexpectedly extreme loads, progressive collapse and structural robustness has recently received a great deal of attention, while the number of scientific papers published on the topic has grown considerably. This paper describes an analysis of the failure of a 106 m3 steel raised wine tank belonging to a local wine producer that suddenly collapsed, fortunately without personal injury, but causing significant damage to the company's facilities. The collapse generated the progressive failure of other tanks next to the first one that failed. After several visits to inspect the accident on site, a diagnosis was made to determine the causes. Possible reasons were examined by visual inspections and experimental tests on steel specimens recovered from the collapsed structures, which allowed to determine the mechanical properties and study the fracture surfaces by scanning electron microscopy and micrographs. On the other hand, the load-carrying capacities of the structure were studied by a linear-static finite-element and a nonlinear-static push-over analysis. The collapse mechanism of the system was found to be due to cyclic horizontal loads generated by a pressurized air injection system. The results allowed to conclude that this type of structure is highly vulnerable to horizontal loads and has very little capacity to activate alternative loas paths. The paper also describes a possible solution that could be used to improve the mechanical performance of this structural typology against horizontal loading, based on the lessons learned from the experience.

Application of a Design for Excellence Methodology for a Wireless Charger Housing in Underwater Environments

A major effort is put into the production of green energy as a countermeasure to climatic changes and sustainability. Thus, the energy industry is currently betting on offshore wind energy, using wind turbines with fixed and floating platforms. This technology can benefit greatly from interventive autonomous underwater vehicles (AUVs) to assist in the maintenance and control of underwater structures. A wireless charger system can extend the time the AUV remains underwater, by allowing it to charge its batteries through a docking station. The present work details the development process of a housing component for a wireless charging system to be implemented in an AUV, addressed as wireless charger housing (WCH), from the concept stage to the final physical verification and operation stage. The wireless charger system prepared in this research aims to improve the longevity of the vehicle mission, without having to return to the surface, by enabling battery charging at a docking station. This product was designed following a design for excellence (DfX) and modular design philosophy, implementing visual scorecards to measure the success of certain design aspects. For an adequate choice of materials, the Ashby method was implemented. The structural performance of the prototypes was validated via a linear static finite element analysis (FEA). These prototypes were further physically verified in a hyperbaric chamber. Results showed that the application of FEA, together with well-defined design goals, enable the WCH optimisation while ensuring up to 75% power efficiency. This methodology produced a system capable of transmitting energy for underwater robotic applications.

Design Optimization of Lattice Structures under Compression: Study of Unit Cell Types and Cell Arrangements.

Additive manufacturing enables innovative structural design for industrial applications, which allows the fabrication of lattice structures with enhanced mechanical properties, including a high strength-to-relative-density ratio. However, to commercialize lattice structures, it is necessary to define the designability of lattice geometries and characterize the associated mechanical responses, including the compressive strength. The objective of this study was to provide an optimized design process for lattice structures and develop a lattice structure characterization database that can be used to differentiate unit cell topologies and guide the unit cell selection for compression-dominated structures. Linear static finite element analysis (FEA), nonlinear FEA, and experimental tests were performed on 11 types of unit cell-based lattice structures with dimensions of 20 mm × 20 mm × 20 mm. Consequently, under the same relative density conditions, simple cubic, octahedron, truncated cube, and truncated octahedron-based lattice structures with a 3 × 3 × 3 array pattern showed the best axial compressive strength properties. Correlations among the unit cell types, lattice structure topologies, relative densities, unit cell array patterns, and mechanical properties were identified, indicating their influence in describing and predicting the behaviors of lattice structures.

The effect of layer orientation angle and its increasing on mechanical properties of laminated material: A numerical study

The mechanical properties of a laminated material due to different layer orientation angle and pattern of layers are simulated using the finite element method. The aim of this paper is to determine the effect of the different layer orientation angles and patterns on the mechanical properties of laminated material. Stainless steel laminated with epoxy carbon is used in this study. The model is a rectangle plate with 150 mm in length, 80 mm in width, and 4 mm in thickness. Linear static finite element analyses with 0,63 MPa normal force is applied to the three various models with different layer orientation angles and patterns. The results show that different layer orientation angles and numbers affect the mechanical properties of the material.

Design Validation Methodology for Bicycle Frames Using Finite Element Analysis

Abstract The general industrial practice for bicycle frame design is to do a prototype testing based on the results from linear static structural finite element analysis (FEA). But many times simulation results are not be in line with laboratory test results such as “fast vibration test rig” used validating the prototype frame structure. Hence, an effort has been made for identifying a FE methodology that would reduce the development time and the test is reliable. In this work, two simulation methodologies were studied – linear static analysis considering test rig boundary conditions and fatigue using harmonic analysis. Both methodologies were compared with laboratory test rig results. The stress amplitude calculated using harmonic fatigue analysis was one third of test rig (experimental) stress amplitude. Also, the stresses calculated using FE static analysis was in line with experimental results. Therefore, a fatigue using harmonic stress calculations is recommended prior to prototype testing using “fast vibration test rig” for reliability. With bicycle industry expected to expand multi-fold and its design validation criteria could include more constraints, these results could help the industry benchmark its design and testing

Influence of Preparation Depth and Design on Stress Distribution in Maxillary Central Incisors Restored with Ceramic Veneers: A 3D Finite Element Analysis.

To evaluate the influence of different preparation designs and depths on the stress field developed in maxillary central incisors restored with veneers made with different ceramic materials using finite element analysis (FEA). A linear static three-dimensional finite element analysis model was used with the aid of reverse engineering to develop digital models of maxillary central incisors restored with ceramic veneers, according to two different preparation depths (thin vs deep) and two different preparation designs (feather edge vs butt joint). Three ceramic systems were tested: (i) feldspathic porcelain, (ii) heat pressed glass ceramic IPS Empress 2 (Ivoclar Vivadent AG), and (iii) heat pressed glass ceramic IPS e.max-Press (Ivoclar Vivadent AG). Each model was subjected to a compressive force of 200N applied to the palatal surface 2 mm below the incisal edge. The longitudinal axis of the restored tooth formed an angle of 130o with the direction of the force. The biomechanical behavior of the different models was examined according to the von Mises stress criterion. Statistical analysis was performed using nonparametric confidence interval estimation using bootstrapping. The maximum observed stress values were calculated and found to be similar between prepared and intact teeth. The cervical margin of the veneers displayed the highest von Mises stress values. Irrespectively of the depth and preparation design, the biggest von Mises stress values were observed at the veneer structures with the following order: (i) IPS Empress 2, (ii) IPS e.max-Press, (iii) feldspathic (p = 0.001). Preparation depth resulted in statistically significant differences (p = 0.001) in the stress distribution in the majority of tested structures. As the preparation depth was increased, the stresses within the veneer structure and the tooth structures were decreased. No statistically significant differences were detected in the stresses among the different restored models, when the preparation design was considered. This FEA study suggests that ceramic veneers could restore the biomechanical behavior of prepared central incisors and made it similar of that of an intact tooth. Regardless of the preparation depth and design and the ceramic system used, the cervical margin of ceramic veneers presents the highest von Mises stress values. When feldspathic porcelain was compared with lithium disilicate (IPS e.max Press), the latter displayed the lowest transfer of stresses to dental tissues. An increase in preparation depth resulted in a statistically significant stress decrease in both the veneer and the tooth.

Fracture prediction on patient-specific tibia model with Osteogenesis Imperfecta under various loading direction

This study aims to predict the fracture of bone with osteogenesis imperfecta (OI) by considering the homogenization properties of real patient. A Type-III of osteotomy in OI femur was used as bone specimen. Nine representative volume element (RVE) models were developed based on μCT-images of bone specimen. Homogenized properties particularly the Young’s moduli of the RVEs was obtained based on homogenization theory in Voxelcon software. The obtained homogenized properties were then assigned to the OI patient-specific model that was developed from CT-images of real patient. The fracture of OI bone was predicted based on linear static analysis and finite element method under loadings of activity daily living (ADL). The results found that the fracture might be happen to the patient under jumping load case, whereas the subject is expected to be safe under standing still and walking load case.

Influence of different wave load schematisation on global ship structural response

ABSTRACTToday, Classification societies cover all the aspects about linear static finite element (FE) analysis through different design guidelines that help structural designers to streamline the design process and make Rule-requested structural verification of the proposed design. Structural modelling aspects are well defined, but for the wave load modelling some questions arise. Wave pressure distribution can be defined using direct wave calculations (e.g. the panel method) or using the Rule formulae definition. This paper presents a benchmark study carried out by the ISSC2018 Committee II-1 Quasi-Static Response. The objective was to investigate and compare alternatives to discretise and implement Rule-defined wave loads from classification societies on global FE models, and its impact on the global structural response. Results from calculations are presented on two ship types. Findings highlight the importance of identifying the lowest level of simplification in order to capture physical phenomena while minimising errors and inaccuracy in direct structural analyses results.

How well does a linear static finite element analysis predict measured strains from a nuclear package tie-down system during rail transportation?

Freight rail is often the preferred method for transportation of dangerous goods. One particular application is the use of rail to convey radioactive material in purpose-built packages. During transit, packages are secured to a rail wagon bed with a tie-down system. The design of tie-down systems varies considerably depending on the package type and rail vehicle; for example, shackles, turnbuckles, tie rods, gravity wells or transport frames are all commonly used. There are also a large number of different packages in existence that all vary in size and mass, typically 1–7 m in length and 100 kg–100 t in mass. Despite the uniqueness of many transport configurations, the design of tie-down systems is always carried out using a limited set of design load cases as defined in the appropriate Codes of Practice and Standards. Many authors have suggested that the load cases within the standards need revision or question which load cases should apply to which scenario. In a previous experiment, accelerations and strains have been measured on a freight wagon and transport frame of a heavy package during a routine rail journey. From these data, a new insight into the magnitude and nature of loading has been gained. In the present study, the measured accelerations have been used as input to a finite element model of the transport frame, and a method based on correlation between predicted and measured strains has been developed to determine an appropriate low-pass filter cut-off frequency, fc, which separates quasi-static loading from raw dynamic data. The residual dynamic measurements have been assessed using signal processing techniques to understand their significance. The finite element model has also been used to assess the presence of contact and boundary nonlinearities and how they affect the agreement between measured and predicted strains.

FINITE ELEMENT ANALYSIS OF JACKETED REINFORCED CONCRETE COLUMN SUBJECTED TO AXIAL AND UNIAXIAL LOAD

One strategy for the jacketing of reinforced concrete column is to target the improvement of local vulnerabilities in columns related to inadequate strength (compressive & Flexural) or poor ductility. Theoretical analysis have been carried out in the present study for different column sections of jacket thickness of 75mm and 100mm for jacketed RC columns subjected to axial and uni-axial compressive loading. The uni-axial load carrying capacity along the major axes has been carried out under balanced section condition. Linear static finite element analysis has been carried out for the jacketed RC columns to compare the confined concrete strength (fcc) of finite element analysis with that of theoretical analysis, to plot the variation of stresses at the central core concrete and at the interface of old and new concrete. The maximum shear stress for the columns is also noted down. The displacement at core with respect to major axis is also plotted.

Comparisons of Linear and Nonlinear FEA of Adhesively Bonded Beams

The effect of boundary conditions on the stress distributions in single-lap adhesively bonded cantilevered beams has been investigated using the three-dimensional linear static and non-linear quasi-static finite element method. The displacement obtained from the linear static and the non-linear quasi-static analyses are compared under the same deformation scale factor for three typical boundary conditions. The analysis results indicate that there are significant differences between the linear static and non-linear quasi-static analyses only if there are significant bending effect on the bonded section. The bigger the bending effect on the bonded section, the bigger the difference between the linear static and non-linear quasi-static analyses.

EFESTS: Educational finite element software for truss structure. Part II: Linear static analysis

This article presents a complete guide from the linear static finite element theory to the software development of the educational finite element software for truss structure (EFESTS). First, linear static formulations of truss structure are summarized, including the element formulation, element assembly and solution. Object-oriented programming is introduced to design the software architecture. Furthermore, the relations between the classes and their instances are clearly described using the static class diagram and the dynamic sequence diagram, respectively. Finally, the linear static solver is intuitively verified by the deformable configuration and stress contour of a 50-bar truss structure. More importantly, a visualization of graphical user interfaces is developed to dynamically assemble the element matrix into the truss matrix, which used to be one of the most difficult skills for students to master. Finally, this software is free for educational research and can be downloaded from the website: http://www.zuowenjie.net/efests.html . In the future, we will develop the geometric nonlinear static analysis solver for the truss structure.

Seismic fragility of regular masonry buildings for in-plane and out-of-plane failure

The seismic vulnerability of stone masonry buildings is studied on the basis of their fragility curves. In order to account for out-of-plane failure modes, normally disregarded in past studies, linear static Finite Element analysis in 3D of prototype regular buildings is performed using a nonlinear biaxial failure criterion for masonry. More than 1100 analyses are carried out, so as to cover the practical range of the most important parameters, namely the number of storeys, percentage of side length in exterior walls taken up by openings, wall thickness, plan dimensions and number of interior walls, type of floor and pier height-to-length ratio. Results are presented in the form of damage and fragility curves. The fragility curves correspond well to the damage observed in masonry buildings after strong earthquakes and are in good agreement with other fragility curves in the literature. They confirm what is already known, namely that buildings with stiff floors or higher percentage of load-bearing walls are less vulnerable, and that large openings, taller storeys, larger number of storeys, higher wall slenderness and higher ratio of clear height to horizontal length of walls increase the vulnerability, but show also by how much.

Finite Element Analysis of Worm Auger in Meat Grinder

The worm auger contributes to the pressures generated at the grinder plate face during grinding of meat. The axial pressure distribution along the worm auger during grinding was discussed. The pressure almost increased linearly along axial direction from feeding end to discharge end. The 3D model of the worm auger created in Pro/E software were imported into ANSYS 9.0 software and a linear static finite element analysis was performed. The visual deflection patterns the part experiences under "real world" loading conditions were obtained so as to complete the security check of strength. The results showed that the yield strength was largely improved with thread root radius increasing from 2 mm to 5 mm. Hence, this method can be applied to rapidly and correctly find those dangerous positions and existing imperfections of its structure, thus providing valuable data to judge its structural rationality before practical manufacture, so as to make further improvements and optimizations for its structural design.

Three-Dimensional Non-Linear FE Analysis of Shear Stress Distributions in Adhesively Bonded Joint

The aim of this work is to investigate the shear stress distributions across the adhesive layer thickness in single-lap adhesively bonded joint. The shear stress distributions of a single-lap adhesively bonded joint have been investigated using the three-dimensional linear static and non-linear quasi-static finite element method. The analysis results indicate that there are significant differences between the linear static and non-linear quasi-static analyses. The results also show that the maximum value of the shear stress component S13 occurs at the centre line while the maximum of the shear stress components S12 and S23 occur near or at the left-rear corner of the adhesive layer.

Non-linear idealisation error analysis of an aerospace stiffened panel loaded in compression

The SAFE Structural Analysis procedure is an idealisation error control methodology devised for linear static finite element analysis. This study examines the applicability of this process to non-linear problems. The studied case is the collapse analysis of an aircraft stiffened panel loaded in compression. This article presents the critical investigation of important modelling assumptions, including the joint modelling, boundary conditions, geometrical imperfections and scattering in material parameters. Potential error sources are identified and then analysed using the non-linear finite element solver ABAQUS. The analysis derived an improved finite element model and concrete idealisation error estimates. The finally simulated failure behaviour corresponds well to the data measured in the test.

Finite Element Analysis of Grinder Plate with Bone-Removal Facilities

The grinder perforated plate with bone-removal systems has a unique design to improve the quality of ground meat. The pressure distribution on the grinder knife/plate interface during grinding of meat was investigated. The peripheral pressure on meat grinder plates during operation was greater than at the center thus hard particles are collected at the low pressure point. The mechanical models on the perforated plate surface created in MATLAB 7.0 for linear programming, and the 3D model of the perforated plate created in Pro/E software were imported into ANSYS 9.0 software and a linear static finite element analysis was performed. The visual deflection patterns the part experiences under "real world" loading conditions were obtained so as to complete the security check of strength.

Simulation of the vertical bending fatigue test of a five-link rear axle housing

This study seeks a practical method for simulating the vertical bending fatigue test of the BANJO housing of a five-link rear axle. Linear static and transient dynamic finite element models are constructed for the rear axle in which the rubber bushings and the bearings of the axle shafts are reasonably modeled with solid and shell elements, respectively, for simplicity. The calculated results are compared with the measured strain histories, and the results indicate that the finite element models constructed are reasonable. The hypothesis of equal fatigue damage is applied to determine the Hainan proving ground driving life prediction that is equivalent to the constant amplitude fatigue life in the vertical bending fatigue test.