Beam Finite Element Model Research Articles

Deformation Behavior of the Percolating Eutectic Intermetallic in HPDC and Squeeze-Cast Mg Alloys

The structural compliance of the spatially interconnected intermetallic network in a squeeze-cast MRI230D alloy was determined using focused ion beam (FIB) data and finite element (FE) modeling, and compared with data for a high-pressure die-cast AZ91D and three binary Mg-RE alloys from the existing literature. The respective elastic responses were sorted out into two characteristic behaviors: for eutectic volume fractions less than ~22% the behavior was akin to that of highly compliant, bending-dominated structures, whereas for larger fractions, it reproduced that of structurally efficient, stretch-dominated microtruss structures. In all cases, the contribution from the interconnected network added to the total strength of the alloy an amount comparable with the strengthening expected from a similar volume fraction of dispersed particles. Being more compliant, the bending-dominated structures appeared less prone to developing damage by cracking at low strains than the stretch dominated ones.

Numerical investigation on mechanical properties of cellular lattice structures fabricated by fused deposition modeling

Cellular lattice structures (CLS) with designed structural integrity are highly demanded in many applications such as light-weight industrial components and bone scaffold. In recent years, additive manufacturing (AM) processes have been found to be capable of producing such products with controllable porosity and pore sizes. However, AM faces an inherent obstacle so that the CLS strut diameter varies along its length. This study uses finite element modeling to predict the effect of variation in the struts׳ diameter on the elastic modulus as well as collapse stress of CLS using both beam and solid finite elements. To determine the mechanical behavior of the lattice and bulk material, lattice structures as well as compression test specimens are fabricated using fused deposition modeling. The results show that the beam finite element model is stiffer than the solid one since the beam model cannot capture the effects of material concentration at the points of diameter variations. However, the obtained elastic modulus does not differ significantly between solid and beam models while the difference is not negligible for collapse stress.

Finite Element Modeling of Insulated FRP-Strengthened RC Beams Exposed to Fire

The fire performance of reinforced concrete (RC) members strengthened with externally bonded fiber-reinforced polymer (FRP) laminates has been an issue of significant concern, particularly for building applications. To achieve structural fire-resistance ratings as specified in building design codes, an insulation layer often needs to be provided. This paper presents the first three-dimensional finite element (FE) approach for the fire performance simulation of insulated FRP-strengthened RC beams. The proposed approach gives careful considerations to the constitutive modeling of concrete, steel, and FRP, as well as the bond-slip behavior of FRP-to-concrete and steel-to-concrete interfaces. Comparisons between FE predictions and existing test data are presented to demonstrate the accuracy of the proposed FE approach. Numerical results obtained with the present FE approach show that the assumption of perfect bonding between FRP and concrete as adopted in previous numerical approaches leads to underestimations of deflections and thus unsafe predictions of fire resistance. The FE approach presented in the paper can be directly applied in performance-based fire safety design, or in parametric studies aimed at developing simplified design rules.

Analysis of Operational Modal Identification Techniques Performances and their Applicability for Damage Detection

Operational modal identification techniques, also known asAmbientmodal orOutput Onlymodal, have been in recent years object of growing interest within several applications typical of civil, mechanical and aerospace engineering. In this paper, two of them, known as EFDD and SSI, are fully implemented by means of in-house codes and applied on a finite element beam model dynamic response time data, in order to evaluate their accuracy, focusing on the lowest system’s natural frequencies. Assessments of the techniques’ robustness to a disturbance in the random excitation, reliability when implementing on a small number of measurement channels and in localization and quantification of a given damage in multiple sites are also performed and presented.

Study on Factors of Axial Crushing of Thin-Walled High-Strength Steel Sections Used in Passenger Car

This paper firstly studied the structure of front longitudinal, then reviewing comprehensive literature draw the similarity of collision of the thin-walled tube and front longitudinal,finally ensure the study of collision of the thin-walled tube. And establishing three kinds of thin-walled welded rectangular beam finite element model of spot welding, seam welding and laser welding, arrive a more superior technology through researching and analyzing the model.

Identification of System Properties in a Square Frame Undergoing Large Deformations: Numerical and Experimental Investigations

The aim of this paper is to highlight and identify the influencing parameters of the nonlinear behavior of highly deformable structures. Therefore, as an example, a large deformable square frame consisting of four slender members of equal length has been investigated experimentally. Based on highly resolving measurements using the digital image correlation method (DIC), the inverse problem of nonlinear system identification has been solved by an automatic parameter identification algorithm. For this purpose, a numerical model is set up with a beam finite element model using the absolute nodal coordinate formulation (ANCF), which enables the modeling of geometrical and possible material nonlinearities. The influencing parameters as well as the system properties have been determined by using a genetic optimization algorithm. The impact of the main influencing parameter is carved out by an included sensitivity study. The final model with automatically identified parameters shows high agreement with the experimental setup. With this approach the influences and nonlinearities, e.g. material parameters, rigid behavior, real boundary conditions, etc., come up to surface leading to a deeper understanding of the structural behavior of the system itself. Therefore, the present approach can be utilized for further investigations of nonstandard structures undergoing large deformations.

A negative derivative feedback design algorithm

Vibration control logics based on the modal approach allow damping to be increased on a certain number of modes. The main limit associated with these strategies is represented by spillover on non-modelled modes. Negative derivative feedback (NDF) proves particularly robust against spillover since modal velocity is fed back through a band-pass filter so that undesired effects can be limited both at high and low frequencies. Unfortunately, the definition of the control gains for this logic is generally more difficult than other resonant controls owing to the lack of physical meaning. In this paper a design strategy for an NDF controller based on an optimal approach is proposed for single and multi-degrees of freedom systems and is tested on a cantilever beam finite element model.

Single-beam analysis of damaged beams: Comparison using Euler–Bernoulli and Timoshenko beam theory

Abstract A new general formulation that is applicable to the damaged, linear elastic structures ‘unified framework’ is used to obtain analytical expressions for natural frequencies and mode shapes. The term mode shapes is used to mean the displacement modes, the section rotation modes, the sectional bending strain modes and sectional shear strain modes. The formulation is applicable to damaged elastic self-adjoint systems. The formulation has two unique aspects: First, the theory is mathematically rigorous since no assumptions are made regarding the physical behavior at a damage location, therefore there is no need to substitute the damage with a hypothetical elastic element such as a spring. Since the beam is not divided at the damage location, rather than an 8 by 8, only a 4 by 4 matrix is solved to obtain the natural frequencies and mode shapes. Second, the inertia effects due to damage which have till now been neglected by researchers are accounted for. The formulation uses a geometric damage model, perturbation of mode shapes and natural frequencies, and a modal superposition technique to obtain and solve the governing differential equation. Timoshenko beam theory is then taken as an example, and its results are compared with results using Euler–Bernoulli beam theory and finite element models. The range of applicability of the two theories is ascertained for damage characteristics such as depth and extent of damage and beam characteristics such as slenderness ratio and Poisson׳s ratio. The paper considers rectangular notch like non-propagating damage as an example of the damage.

A finite element beam model including cross-section distortion in the absolute nodal coordinate formulation

A new class of beam finite elements is proposed in a three-dimensional fully parameterized absolute nodal coordinate formulation, in which the distortion of the beam cross section can be characterized. The linear, second-order, third-order, and fourth-order models of beam cross section are proposed based on the Pascal triangle polynomials. It is shown that Poisson locking can be eliminated with the proposed higher-order beam models, and the warping displacement of a square beam is well described in the fourth-order beam model. The accuracy of the proposed beam elements and the influence of cross-section distortion on structure deformation and dynamics are examined through several numerical examples. We find that the proposed higher-order models can capture more accurately the structure deformation such as cross-section distortion including warping, compared to the existing beam models in the absolute nodal coordinate formulation.

A Dual Grid Curved Beam Finite Element Model of Piston Rings for Improved Contact Capabilities

A Dual Grid Curved Beam Finite Element Model of Piston Rings for Improved Contact Capabilities

Modeling and prediction of the strength based on the time factor in tower construction

On the basis of the documentation, the finite element beam model of the Shukhov’s tower has been constructed. In 1970–1971, after 50 years of exploitation, the study of the Shukhov’s tower was conducted by the specialists. This study has revealed serious defects of the individual elements. It was found that the rolled profiles reaches 10 % of the cross section due to corrosion and the calculated resistance of the individual components is in the range of 170 MPa, which is somewhat lower than the standard values. In the present work the time factor is taken into account as a reduction of the wall thickness of the metal profiles. In this article the state of the stress under the own weight has been examined when the wall thickness corresponds documentation (1921) and after reducing the thickness by 2 mm (2011). Stability analysis has been performed taking into account only the compressive load from the own weight. In this paper the main frequencies and modes of vibration of the tower model, depending on the thickness of the profile wall have been calculated. The results were obtained under the assumption that the loss of thickness of the metal profiles of the tower is accompanied by the proportional loss of the own weight.

An Expansion Method Dealing with Spatial Incompleteness of Measured Mode Shapes of Beam Structures

Obtaining mode shape values at rotational degrees of freedom (dofs) is a challenge from dynamic test of beam structures, for the reason that rotational dofs are usually difficult to be measured. This article proposes an expansion method to deal with spatial incompleteness of measured mode shapes of beam structures. One improvement is that the constrained linear least squares is combined into traditional expansion procedure proposed by Liu (2011), to estimate modeling errors in a physical meaning interval; and the initial guesses on mode-correction coefficients could be obtained using a non-iterative technique for improving the convergence of the approach. A cantilever beam is used to investigate the proposed method by establishing two numerical models: one is a beam finite element model as a baseline; the other is the model to represent real structure with different stiffness distribution compared with the baseline. One can conclude from numerical results that the approach has a better convergence performance than traditional expansion method, and spatially incomplete measured modes for beam structures, including higher order modes, can be expand properly and to be fundamental modal data for model updating or damage detection of beam structures.

Global buckling analysis model for thin-walled composite laminated beam type structures

This paper presents a beam finite element model for non-linear global buckling analysis of composite laminated beam type structures. To perform the non-linear stability analysis, the framework of updated Lagrangian incremental formulation is used. The non-linear displacement field of thin-walled cross-section is adopted in order to insure the geometric potential of semitangential type for both the internal torsion and bending moments. The cross-section mid-line contour is assumed to remain not deformed in its own plane and the shear strains of middle surface are neglected. The laminates are modeled on the basis of classical lamination theory. In order to illustrate the application of the proposed formulation, several numerical examples are presented. For validation purposes, the obtained results are compared with results reported in the literature and the ones obtained with shell finite elements by Nastran.

Finite Element Modelling of Steel Beams with Web Openings

Height limitations are not uncommon in multi-storey buildings due to economic requirements and esthetical considerations. Substantial spaces are normally required to enable the passage of large pipes and ducts beneath steel beams leading to uneconomic floor heights. The most adopted solution for this issue is the use of steel beam web openings to provide the required space for services. These openings could lead to a significant decrease of the beam load carrying capacity depending on the adopted openings shape, size and location. These aspects motivated the present study based on FE simulations calibrated against numerical and test results. The results accuracy enabled a comprehensive parametric analysis of beams with web openings to be made focused on the profile size, web opening location, among others. The study also investigated the efficiency of longitudinal stiffeners welded at the opening region and benefits of using an adequate edge concordance radius in beams with rectangular and square openings. The obtained results showed the need of using welded longitudinal stiffeners in order to increase the beams ultimate load carrying capacity. This adoption can double or even triple the ultimate load of beams with rectangular and square opening heights equal to 0.75 H, respectively.

Prediction of TBM tunnel segment lining forces using ANN technique

본 논문에서는 TBM 터널의 세그먼트 라이닝 설계 자동화 기술 개발의 일환으로 인공신경망기법을 이용한 세그먼트 라이닝 부재력 산정기법 개발에 관한 내용을 다루었다. 부재력 평가가 가능한 인공신경망을 개발하기 위해 먼저 다양한 설계조건을 도출하고 이에 대해 2-Ring Beam 모델을 이용한 유한요소해석을 수행하여 인공신경망 학습에 필요한 설계조건별 부재력에 관한 DB를 구축하였다. 구축된 DB를 활용하여 인공신경망의 최적화 과정을 통해 최대 부재력 및 분포도를 예측할 수 있는 인공신경망을 구축하였다. 검토 결과 구축된 인공신경망은 유한요소해석과 동일한 정밀도의 부재력 산정 기능을 확보하는 것으로 검토되었으며 따라서 TBM 세그먼트 라이닝 설계시 필요한 부재력 평가를 위한 효율적인 수단으로 활용될 수 있는 것으로 판단된다. This paper presents development of artificial neural network(ANN) based prediction method for section forces of TBM tunnel segment lining in an effort to develop an automatized design technique. A series of design cases were first developed and subsequently analyzed using the two-ring beam finite element model. The results were then used to form a database for use as training and validation data sets for ANN development. Using the database, optimized ANNs were developed that can readily be used to predict maximum sectional forces and their distributions. It is shown that the compute maximum section forces and their distributions by the developed ANNs are almost identical to the computed by the two-ring beam finite element model, implying that the developed ANNs can be used as design tools which expedite routine design calculation process. The results of this study indicate that the neural network model can be effectively used as a reliable and simple predictive tool for the prediction of segment sectional forces for design.

Immediate Deflection of Pretensioned Inverted T-Beam with Circular Web Openings Strengthened with GFRP Using Response Surface Methodology

The urgent need for a web opening in the pretensioned inverted T-beams after the construction for essential services causes local cracking around the opening which leads to decrease in stiffness and load carrying capacity. Therefore, strengthening the vicinity of the opening is essential to restore the loss in load carrying capacity of the beam using GFRP. To study the deflection of pretentioned inverted T-beam with web opening, three-dimensional finite element beam models are developed before and after GFRP strengthening using the finite element analysis (FEA). Modeling methodology and nonlinear analysis approach in ANSYS are presented. The results obtained from the FEA beam model are compared with the test data in terms of load-deflection curve. It has been concluded that FEA models are good representations for GFRP strengthened beams with web openings in terms of the number of elements, structural details, and, especially, reasonably accurate results in general.

On the Numerical Identification of System Properties in a Square Frame

AbstractIn this paper the influencing factors of the nonlinear behavior of a highly deformable square frame are aimed to highlight and identify. Therefore, in a first step a square frame consisting of four slender members of equal length has been investigated experimentally. Subsequently to these investigations, a numerical model is set up with a beam finite element model, which is based on the absolute nodal coordinate formulation (ANCF), including geometrical and possible material nonlinearities. The influencing factors as well as the system properties are identified by using a genetic optimization algorithm. The final results show that the highly nonlinear behavior of the square frame can be reproduced accurately in case the nonlinear characteristics of the joints are taken into account carefully. The numerical model combined with the system parameter identification can be utilized for further numerical investigations of non‐standard structures undergoing large deformations. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A model-free damage identification method for flexural structures using dynamic measurements from distributed long-gage macro-strain sensors

A damage identifying algorithm, named modal macro-strain vector, has been verified as efficient to locate local damages for flexural structures, with modal parameters directly extracted from the dynamic macro-strain measurements. However, the basic relation between the change in modal macro-strain vector and damage severity has not been established yet. In this article, a model-free damage identification method is proposed based on the modal macro-strain vector method to implement both damage location and quantification. In this method, one assumption is first proposed that the normalized modal macro-bending-moment is constant, as proved by the simulations. Then, damage quantification is performed with the combination of the spatial parameter of neutral axis and normalized modal macro-strain vector. In view of these, different finite element beam models are simulated with several damage cases for each specimen to verify the method. Simulation results show that the damage severity can be evaluated with a high accuracy with the proposed method. As a result, the efficiency of the method is verified through the experiments of a steel beam in the laboratory. Therefore, the proposed system is proved to be effective and useful for structural health monitoring.

Electrode size dependence of piezoelectric response of lead zirconate titanate thin films measured by double beam laser interferometry

The electrode size dependence of the effective large signal piezoelectric response coefficient (d33,f) of lead zirconate titanate (PZT) thin films is investigated by using double beam laser interferometer measurements and finite element modeling. The experimentally observed electrode size dependence is shown to arise from a contribution from the substrate. The intrinsic PZT contribution to d33,f is independent of electrode size and is equal to the theoretical value derived assuming a rigid substrate. The substrate contribution is strongly dependent on the relative size of the electrode with respect to the substrate thickness. For electrode sizes larger than the substrate thickness, the substrate contribution is positive and for electrode sizes smaller than the substrate thickness, the substrate contribution is negative. In the case of silicon substrates, if the electrode size is equal to the substrate thickness, the substrate contribution vanishes, and the measured value of d33,f is equal to the theoretical value under the rigid substrate assumption.

Long-term prediction of combined wave and whipping bending moments of container ships

The purpose of this paper is to propose a practical computational procedure for the long-term distribution of combined wave and whipping bending moments (BMs) of container ships. The problem is formulated in the frequency domain using standard engineering tools for load computation: a seakeeping code for the rigid-body response and a beam finite element model for transient vibratory response. The von Karman approach with correction for pile-up effect is employed for bow flare slamming load assessment. Correlation between wave and whipping BMs is considered. The procedure is demonstrated on the example of a 9200 TEU container ship. Long-term distributions of combined BMs are computed using the standard International Association of Classification Societies scatter diagram for the North Atlantic environment and two additional scatter diagrams for common shipping routes of container ships. The speed profile required for the long-term load prediction is calculated by the seakeeping analysis respecting operability limiting criteria. Conclusions about influence of various environmental and operability parameters are drawn.