Finite Element Structural Analysis Program Research Articles

Effect of Restorative Crown of Different Cuspal Inclination and Occlusal Contact on Stress Distribution in Mandibular Second Premolar with Different Ferrule Configuration and Peripheral Bone- 3D Finite Element Analysis

Background: Restoration of pulpless teeth have been difficult because of coronal loss from dental caries, diminished moisture content, endodontic therapy and fractures, resulting in prone to fracture of the tooth during function. Cast metallic band enclosing around cervical surface of a tooth is called ferrule. The role of ferrule is to assist in strengthening the endodontically treated tooth.
 Purpose: In case of ferrule less tooth, the post performs as a wedge and may result in root fracture. Therefore modification in design of ferrule is required. Presence or absence of ferrule of coronal dentin influenced stress distribution pattern within tooth structure. Failure or success of a restoration may be influenced by on how the stress is dispersed to the tooth structure so it is essential to study the stress dispersal pattern within tooth and associated structure.
 Materials and Methods: A three-dimensional FE method (FEM) will be carried out for study and finite element structural analysis programs will be HYPERMESH 11 and ANSYS 18.1 software. Eight 3D models will be created to simulate endodontically restored mandibular second premolar with different coronal dentin configurations. The complete crown will be modeled with a 20-degree, 33- degree, 45-degree facial cusp inclination. The oblique force of 200 N will be executed to the buccal cusp of mandibular second premolar. Analysis of results will be done by both color-coding and numerically. By using FEA software the von Mises equivalent stress (MPa) will be calculated.

Calculation algorithm of the building of CLT for the Russian Federation

The design of modern CLT structures in Russia is still under development. This calculating algorithm is proposed for designing of the CLT structures in Russia. The calculation of the CLT was carried out in accordance with the Russian codes of SP 64.13330.2017 Timber structures. The calculation algorithm allows, on the one hand, to automate the design and, on the other hand, to calculate the CLT according to the existing Russian codes of SP 64.13330.2017 Timber structures, and from the third, to obtain some necessary value of compression stress perpendicular to the CLT plane. In our case modelling was done in the Revit software for computer-aided design that implements the principle of building information modelling. For comparison internal stresses (shear, tensile and compressive) with the design resistance accordance with Russian codes “CП” calculation results were obtained from the program Dlubal RFEM (finite element structural analysis program).To obtain new values of compression stress perpendicular to the CLT plane and its subsequent verification, there is a branch in the algorithm.

FSI investigation on stability of downwind sails with an automatic dynamic trimming

Gennakers are lightweight and flexible sails, used for downwind sailing configurations. Qualities sought for this kind of sail are propulsive force and dynamic stability. To simulate accurately the flow surrounding a sail, several problems need to be solved. Firstly, the structural code has to take into account cloth behavior, orientation and reinforcements. Moreover, wrinkles need to be taken into account through modeling or fine enough discretization. Secondly, the fluid solver needs to reproduce the atmospheric boundary layer as an input boundary condition, and be able to simulate separation. Thirdly, the fluid-structure interaction (FSI) is strongly coupled due to the lightness and the flexibility of the structure. The added mass is three orders of magnitude greater than the mass of the sail, and large structural displacement occur, which makes the coupling between the two solvers difficult to achieve. Finally, the problem is unsteady, and dynamic trimming is important to the simulation of gennakers (Graf and Renzsch, 2006). As the FSI procedure is detailed in Durand (2012), the present work is rather focused on its application to downwind sail stability.The main objective of this paper is to use numerical simulations to model gennakers, in order to predict both propulsive force and sail dynamic stability. Recent developments from Durand (2012) are used to solve these problems mentioned earlier, using a finite element structural analysis program dedicated to sails and rig simulations coupled with an unsteady Reynolds averaged Navier–Stokes equations (URANSE) solver. The FSI coupling is done through a partitioned approach with quasi-monolithic properties. An arbitrary Lagrangian Eulerian (ALE) formulation is used, hence the fluid mesh follows the structural deformation while keeping the same topology. The fluid mesh deformation is carried out with a fast, robust and parallelized method based on the propagation of the deformation state of the sail boundary fluid faces (Durand et al., 2010).Tests were realized on a complete production chain: a sail designer from Incidences-Sails has designed two different shapes of an IMOCA60 gennaker with the SailPack software. An automatic procedure was developed to transfer data from Sailpack to a structure input file taking into account the orientation of sailcloth and reinforcements. The same automatic procedure is used for both gennakers, in order to compare dynamic stability and propulsion forces. A new method is then developed to quantify the practical stability of a downwind sail.

A Metaheuristic Approach to Skew Reinforcement Optimization in Concrete Shells Under Multiple Loading Conditions

This paper deals with the optimization of reinforcement in concrete shell elements. A metaheuristic approach based on a genetic algorithm is presented and called Skew Reinforcement Design in Reinforced Concrete Two Dimensional Elements with Multiple Loading Conditions (SRD2DMLC): it is an evolution of the method called Skew Reinforcement Design in Reinforced Concrete Two Dimensional Elements (SRD2D) extended to Multiple Loading Conditions (MLC). SRD2D is a design tool written in C++ that could be linked as a post processor to any commercial finite element structural analysis program. The internal actions obtained from elastic analysis of the structure are used to calculate the minimum amount of reinforcement able to guarantee structural safety. SRD2D is able to handle only one load condition at a time, but in everyday design situations a structure is almost never subjected to a single load case, but to a large number of them. Different load arrangements are, in fact, chosen to address all the possible situations that the structure can undergo in its life. SRD2DMLC is able to determine (SRD2DMLC determines or SRD2DMLC can be used to determine) the minimum reinforcement required to address all the simultaneous load cases used in the design of a structural element, that is, the combinations of maximum/minimum internal actions used in the design. The use of SRD2DMLC demonstrates that the total reinforcement able to satisfy multiple load conditions is less than the envelope of the solutions obtained analysing the single load cases alone with SRD2D. SRD2DMLC has been validated against SRD2D and Microsoft Excel solver on a prestressed curved slab bridge showing an average gain respectively of 3 and 14%.

Experimental analysis on FEM definition of backfill-rectangular tank-fluid system

In the present study, the numerical and experimental investigations were performed on the backfill- exterior wall-fluid interaction systems in case of empty and full tanks. For this, firstly, the non-linear three dimensional (3D) finite element models were developed considering both backfill-wall and fluid-wall interactions, and modal analyses for these systems were carried out in order to acquire modal frequencies and mode shapes by means of ANSYS finite element structural analysis program. Secondly, a series of field tests were fulfilled to define their modal characteristics and to compare the results from proposed approximation in the selected structures. Finally, comparing the theoretical predictions from the finite element models to results from experimental measurements, a close agreement was found between theory and experiment. Thus, it can be easily stated that experimental verifications provide strong support for the finite element models and the proposed procedures themselves are the meritorious approximations to the real problem, and this makes the models appealing for use in further investigations.

Modeling the EPRI-Wisconsin Power and Light Broken Wire Tests

In the late 1970s, the Electric Power Research Institute and Wisconsin Power and Light performed a series of tests to measure the forces on a power transmission tower due to broken conductors. Three of those tests have been modeled using ADINA, a finite-element structural analysis program with the ability to perform nonlinear time history analyses of dynamic events. When a wire breaks, the time history of the force on the tower typically has two peaks. The first peaks were modeled accurately in time and magnitude. The second peaks were modeled accurately in time; however, the magnitudes were larger than those measured during the tests. The simulated time histories contained high frequencies due to the discretization of the real structure into the finite elements. Numerical filtering was used to remove these modeling artifacts.

Effective Torsional Constant for Restrained Open Section

A simple, easy-to-apply effective torsional constant for the rotational stiffness of a restrained open section was developed. This effective torsional constant takes both the pure torsion and the warping torsion into acccount. The final result is a simple formula for a modified torsional constant, which is in terms of unbraced length and can be easily calculated. The constant then can be used for any generic finite-element structural analysis program.

Automatic FEM Procedure Using a Geometry-Oriented h Version for Plate Structures.

An automatic FEM procedure based on a geometry-oriented h version is presented for a general 3D solid structure combined with many parts of various forms. A simple and efficient method to create the geometry of a solid structure with many parts combined is described. Physical conditions for the structural analysis are given directly on the geometry. Then simply by giving the total number of elements, all input data including the element mesh and constraint equations to combine elements between parts required for a finite element structural analysis program are generated, and the initial analysis is made automatically. By giving only the allowable ratio of the finite element error, the adaptive mesh refinement is made and the detailed analysis is also carried out automatically. A practical PC program based on the present method has been developed. Numerical examples are demonstrated to show the validity and effectiveness of the proposed method.

Implementation of Design Sensitivity Analysis with Existing Finite Element Codes

A numerical method is presented to implement structural design sensitivity analysis theory, using the versatility and convenience of existing finite element structural analysis programs. Design variables such as thickness and cross-sectional areas of components of individual members and built-up structures are considered. Structural performance functionals considered include displacement and stress. The method is also applicable for eigenvalue problem design sensitivity analysis. It is shown that calculations can be carried out outside existing finite element codes, using postprocessing data only. Thus design sensitivity analysis software does not have to be imbedded in an existing finite element code. Feasibility of the method is shown through analysis of several problems, including a built-up structure. Accurate design sensitivity results are obtained without the uncertainty of numerical accuracy associated with selection of finite difference perturbations.

Structured data in structural analysis software

This paper discusses the use of computer data structures in finite-element structural analysis programs. A number of data structure types that have been shown to be useful in such programs are introduced and described. A simple finite-element model is used to demonstrate how the given set of data structure types naturally lend themselves to developing software for the model. Different methods of implementing data structures in the context of a program are discussed.

The Application of Finite Element Methods to the Dynamic Analysis of Flexible Spatial and Co-Planar Linkage Systems

An analytical method is presented for the dynamics of spatial mechanisms containing complex-shaped, flexible links with application to both high-speed industrial machines and robotic manipulators. Existing NASTRAN-type finite element structural analysis programs are combined with 4 × 4 matrix dynamic analysis techniques and Component Mode Synthesis coordinate reduction to yield a procedure capable of analyzing complex, non-linear spatial mechanisms with irregularly shaped links in great detail, yet producing a system of equations small enough for efficient numerical integration. The method is applied to two examples.

Finite element costs

This paper describes an extension to the classical finite element analysis methods. Using the same data inherent in the stiffness matrix, and adding cost parameters as input, a finite element structural analysis program is shown to output cost data. The basic concept is that the material costs are only a fraction of the total costs, which include labor and overhead. It is theorized that the labor and overhead costs may be dominant, and are related to structural complexity and numbers of joints. Two examples are given: a simple four-member truss illustrates the method, and a transmission tower example is offered to demonstrate the principle.

Buckling analysis of laminated composite plates

Over the past few years, fibre-reinforced laminates have been found to be highly desirable for aerospace structural applications. This paper is concerned with one of the problem areas connected with these applications; namely, the stability of midplane symmetric, laminated composite plates. The results of plate buckling analyses performed by means of the BENST module of the PLANS system of finite element structural analysis programs are presented. These analyses involve a wide variation in laminate orthotropic and material axis orientation and a number of plate aspect ratios and support conditions. The efficacy of the BENST finite element program is demonstrated by comparison with published results. Peak buckling loads for simply supported plates at material axes orientation other than the plate principal axes are predicted for laminate material properties ranging from mildly orthotropic to severely orthotropic. This indicates that the common design practice of calculating simply supported plate buckling levels by applying a ‘knock down’ factor to existing clamped plate data may often be unnecessarily conservative. Also included in this paper are details on the finite element method implemented in BENST and the development of the expressions that permit the calculation of laminate effective material properties from the properties of the individual layers.

Fesap—design program for static and dynamic structural analysis

The Structural Analysis Program, SAP, has been widely accepted and modified to perform a wide variety of structural analyses at many universities, government and industrial organizations. This paper will document the development of SAP into a user-oriented program for linear dynamic and static analysis of large complex structures which is referred to as FESAP ( Finite Element Structural Analysis Program). The paper will also describe companion computer programs which constitute a total design system for thermo-structural analysis. The total system includes mesh generation programs, a heat transfer program, the structural analysis program, batch and interactive graphic computer programs, and post-processors for the results of the heat transfer and structural analysis programs.

An improved fluid superelement for the coupled solid‐fluid‐surface wave dynamic interaction problem

AbstractThe dynamic solid‐fluid‐surface wave interaction problem can be solved with known Finite Element solutions. However, these solutions are complicated by the unsymmetric nature of the matrix equation to be solved.This paper shows how the numerical problem can be simplified by symmetrization, without loss of physical generality, using specialized Lagrange co‐ordinates for the fluid free surface wave, and by introducing a Lagrange multiplier representing a generalized fluid pressure.With these improvements, solid‐fluid‐surface wave analysis capabilities can easily be added to most Finite Element structural analysis programs. Numerical examples of the performance of the improved formulation are given for earthquake analysis.

On the Application of Response Limiting to Finite Element Structural Analysis Programs

The inclusion of response limiting or “notching” in random vibration design and test requirements for larger equipments such as spacecraft is becoming more commmon. This type of requirement states that the specified input excitation, usually motion, may be reduced in narrow frequency bands to the degree necessary to limit the response at any of a number of specified locations to a specified maximum response. Laboratory test procedures to implement such requirements have been developed and described in the literature. Clearly it is also desirable to include such notching during the design analysis stage when using finite element structural analysis programs typified by NASTRAN. Exact computation of the notched input excitation and associated system responses is quite complicated and therefore costly. This paper describes a simple, economical method of computing the notched spectrum using an approximation which relies only on reasonably separated peak responses at any response control node and a not unusually small difference in level between the maximum input and maximum response spectral density levels. The method accounts for the modal damping, the specified averaging bandwidth for response control, and any desired number of response control nodes, i.e., locations. An interesting by-product of the analysis was the determination that only 50 percent of the mean square response of a single d.o.f. system to white noise is due to the excitation within the resonant or 3 db bandwidth of the system. Some of the implications of this result with respect to spectral analysis procedures and popular methods of estimating the response of systems to shaped random vibration spectra are discussed.