cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.14325189.v1
title: On Micro-Buckling of Unidirectional Fiber-Reinforced Composites by Means of Computational Micromechanics

description: Abstract Micro-buckling of unidirectional fiber-reinforced composites is investigated in this paper by means of an explicit representation of a geometrically imperfect fiber within the context of kinematical and material non-linear behavior. Two types of fiber imperfections are considered: a helicoidal shape, identified as 3D imperfection; and a sinusoidal plane shape (2D imperfection). Both imperfection models are characterized by a maximum misalignment angle of the fiber with respect to the ideal or perfect configuration, as is usually considered in this field. A total of 816 cases were computed in terms of imperfection type (either 2D or 3D), fiber volume fraction, fiber arrangement (square or hexagonal array), orientation for 2D models, matrix yield stress, and misalignment angle. Two load cases, with constrained and unconstrained transverse strain, were considered. Assuming periodic boundary conditions, homogenization was carried out to obtain macroscopic stresses. Numerical results are compared with an analytical model available in the literature. The results show a high imperfection-sensitivity for small misalignment angles; on the other hand, the type of imperfection and the fiber arrangement do not have a large influence on the results. In addition, it was found that this problem is governed by fiber volume fraction and matrix yield stress only for small imperfections, whereas for large misalignment angles, a change in fiber volume fraction produces small changes in micro-buckling stress.
DOI: 10.6084/m9.figshare.14325309
title: Validation of foam filled tube model and optimization result using Weibull distribution

description: Abstract Passenger safety and low fuel consumption rate are the most important factors that need to be considered when designing modern transportations. This study validates the crash behavior and optimum values of foam-filled structures under the dynamic oblique impact using the Weibull distribution. The optimization method aimed to absorb maximum energy with minimum peak crushing force. Furthermore, the metamodel and optimization techniques such as RBF and NSGA-II were used to ensure accurate validation of the Weibull distribution method. The result showed that the finite element model is comparable to the experimental data in the reference, while the metamodel method, which is directly verified, affects optimization results. The Weibull distribution method shows that the optimum value and the simulation have good accuracy or R2&gt; 0.85.
DOI: 10.6084/m9.figshare.14325309.v1
title: Validation of foam filled tube model and optimization result using Weibull distribution

description: Abstract Passenger safety and low fuel consumption rate are the most important factors that need to be considered when designing modern transportations. This study validates the crash behavior and optimum values of foam-filled structures under the dynamic oblique impact using the Weibull distribution. The optimization method aimed to absorb maximum energy with minimum peak crushing force. Furthermore, the metamodel and optimization techniques such as RBF and NSGA-II were used to ensure accurate validation of the Weibull distribution method. The result showed that the finite element model is comparable to the experimental data in the reference, while the metamodel method, which is directly verified, affects optimization results. The Weibull distribution method shows that the optimum value and the simulation have good accuracy or R2&gt; 0.85.
DOI: 10.6084/m9.figshare.14325180.v1
title: Axial Static Load Dependence Free Vibration Analysis of Helical Springs Based on the Theory of Spatially Curved Bars

description: Abstract This work addresses an accurate and detailed axial static load dependence linearly elastic free vibration analysis of cylindrical helical springs based on the theory of spatially curved bars and the transfer matrix method. For a continuous system, governing equations comprise coupled vibration modes namely transverse vibrations in two orthogonal planes, torsional and axial vibrations. The axial and shear deformation effects together with the rotatory inertia effects are all considered based on the first order shear deformation theory and their effects on the frequencies are investigated. The effects of the initial stress resultants on the frequencies are also studied. After buckling, forward-shifting phenomenon of higher frequencies is noticeably demonstrated. It is also revealed that a free/forced vibration analysis with an axial static load should not be performed individually without checking buckling loads.
DOI: 10.6084/m9.figshare.14325165.v1
title: Tip Deflection Determination of a Barrel for the Effect of an Accelerating Projectile Before Firing Using Finite Element and Artificial Neural Network Combined Algorithm

description: Abstract For realistic applications, design and control engineers have limited modelling options in dealing with some vibration problems that hold many nonlinearity such as non-uniform geometry, variable velocity loadings, indefinite damping cases, etc. For these reasons numerous time consuming experimental studies at high costs must be done for determining the actual behaviour such nonlinear systems. However, using advantages of multiple computational methods like Finite Element Method (FEM) together with an Artificial Intelligence (ANN), many complicated engineering problems can be handled and solved to some extent. This study, proposes a new collective method to deal with the nonlinear vibrations of the barrels in order to fulfil accurate shooting expectancy. Using known analytical methods, in practical, to determine dynamic behaviour of the barrel beam is not possible for all conditions of firing that include numerous varieties of ammunition for different purposes, and each projectile of different ammunition has different mass and exit velocity. In order to cover all cases this study proposes a new method that combines a precise FEM with ANN, and can be used for determining the exact dynamic behaviour of a barrel for some cases and then for precisely predicting the behaviour for all other possible cases of firing. In this study, the whole nonlinear behaviour of an antiaircraft barrel were obtained with 3.5% accuracy errors by ANN trained by FEM using calculated analysis results of ammunitions for a particular range. The proposed FEM-ANN combined method can be very useful for design and control engineers in design and control of barrels in order to compensate the effect of nonlinear vibrations of a barrel for achieving a higher shooting accuracy; and can reduce high-cost experimental works.
DOI: 10.6084/m9.figshare.14325159.v1
title: Robust Multi-objective Optimization Applied to Engineering Systems Design

description: Abstract In engineering systems design, theoretical deterministic solutions can be hardly applied directly to real-world scenarios. Basically, this is due to manufacturing limitations and environmental conditions under which the real system will operate. Therefore, a small variation in the design variables vector can result in a meaningful change on the theoretical optimal design as represented by the minimization of the corresponding vector of objective functions. In this context, it is important to develop methodologies that are able to produce solutions (even suboptimal) that are less sensitive to perturbations in the design variable vector and, consequently, leading to a robust optimal design. In this contribution, first the proposed approach is tested on various mathematical functions. Then, the methodology is applied to the design of two representative engineering systems through multi-objective optimization using the Firefly Colony Algorithm in association with the Effective Mean Concept is presented.The results obtained demonstrate that the design strategy conveyed represents an interesting alternative approach to obtain robust design for a number of engineering applications.
DOI: 10.6084/m9.figshare.14325156.v1
title: Crack Detection Using Mixed Axial and Bending Natural Frequencies in Metallic Euler-Bernoulli Beam

description: Abstract For many years, several crack detection attempts have been using measurements of the structure's modal parameters. One of the easiest is to measure and correlate the change in natural frequencies to cracks. The direct and inverse problem have been discussed in literature. However, the inverse problem, being addressed in this paper, is a challenging one, where it starts by measuring certain structural properties and estimate the corresponding crack location and size. Unlike previous studies that utilizing natural frequencies from one direction, both axial and bending natural frequencies are used together to determine crack size and location, without prior estimation of natural frequencies of the intact beam. The results obtained showing promising capabilities in crack detection.
DOI: 10.6084/m9.figshare.14325147.v1
title: Numerical Study on the Structural Performance of Steel Beams with Slant End-plate Connections

description: Abstract Thermal effects can be one of the most harmful conditions that any steel structure should expect throughout its service life. To counteract this effect, a new beam, with a capability to dissipate thermally induced axial force by slanting of end-plate connection at both ends, is proposed. The beam was examined in terms of its elastic mechanical behavior under symmetric transverse load in presence of an elevated temperature by means of direct stiffness finite element model. The performance of such connection is defined under two resisting mechanisms; by friction force dissipation between faces of slant connection and by small upward crawling on slant plane. The presented numerical method is relatively easy and useful to evaluate the behavior of the proposed beam of various dimensions at different temperatures. Its applicability is evident through satisfactory results verification with those from experimental, analytical and commercially available finite element software. Based on the good agreement between theoretical and experimental methods, a series of design curves were developed as a safe-practical range for the slant end-plate connections which are depend on the conditions of the connection.
DOI: 10.6084/m9.figshare.14325311
title: Hybrid finite-discrete element modelling of rock fracture during conventional compressive and tensile strength tests under quasi-static and dynamic loading conditions

description: Abstract A hybrid finite-discrete element method is proposed to model the rock fracture under various loading conditions. The key component of the hybrid method, i.e. transition from continuum to discontinuum through fracture and fragmentation, is introduced in detail. An empirical relationship between the static strengths and the dynamic strengths derived from the dynamic rock fracture experiments is implemented in the hybrid method to model the effect of loading rate. The hybrid method is calibrated by modelling the Brazilian tensile strength (BTS) test, uniaxial compressive strength (UCS) and notched Brazilian dis tests. Then the hybrid method is employed to model the dynamic rock fracture process in UCS and BTS tests. The proposed method has well modelled the dynamic rock fracture and fragmentation processes and captured the effect of loading rate on rock strengths. It is concluded that the hybrid finite-discrete element is a valuable tool to study the dynamic rock fracture as it takes the advantages of the continuum and discontinuum based method, and considers the effect of loading rate.
DOI: 10.6084/m9.figshare.14325145.v1
title: Free Vibration Analysis of a Liquid in a Circular Cylindrical Rigid Tank Using the Hierarchical Finite Element Method

description: Abstract A hierarchical finite element is developed for the free vibration analysis of a liquid in a rigid cylindrical tank with or without a free surface. It is a hierarchical quadrilateral element and has the advantage that the hierarchical mode number is allowed to vary independently of direction. Liquid behavior in tanks with large aspect ratios can therefore be solved very accurately by using a higher hierarchical mode number in the longer direction than in the shorter one. Furthermore, it is possible to idealize the liquid by using only one element. The solution can therefore be obtained to any desired degree of accuracy simply by increasing the hierarchical mode number. In this method, the liquid behavior is described by the displacements alone. The pressure and velocity potential are not considered as unknowns. The results are compared with other methods and show good agreement.
DOI: 10.6084/m9.figshare.14325311.v1
title: Hybrid finite-discrete element modelling of rock fracture during conventional compressive and tensile strength tests under quasi-static and dynamic loading conditions

description: Abstract A hybrid finite-discrete element method is proposed to model the rock fracture under various loading conditions. The key component of the hybrid method, i.e. transition from continuum to discontinuum through fracture and fragmentation, is introduced in detail. An empirical relationship between the static strengths and the dynamic strengths derived from the dynamic rock fracture experiments is implemented in the hybrid method to model the effect of loading rate. The hybrid method is calibrated by modelling the Brazilian tensile strength (BTS) test, uniaxial compressive strength (UCS) and notched Brazilian dis tests. Then the hybrid method is employed to model the dynamic rock fracture process in UCS and BTS tests. The proposed method has well modelled the dynamic rock fracture and fragmentation processes and captured the effect of loading rate on rock strengths. It is concluded that the hybrid finite-discrete element is a valuable tool to study the dynamic rock fracture as it takes the advantages of the continuum and discontinuum based method, and considers the effect of loading rate.
DOI: 10.6084/m9.figshare.14325100.v1
title: Kelvin Viscoelasticity and Lagrange Multipliers Applied to the Simulation of Nonlinear Structural Vibration Control

description: Abstract This study proposes a new pure numerical way to model mass / spring / damper devices to control the vibration of truss structures developing large displacements. It avoids the solution of local differential equations present in traditional convolution approaches to solve viscoelasticity. The structure is modeled by the geometrically exact Finite Element Method based on positions. The introduction of the device's mass is made by means of Lagrange multipliers that imposes its movement along the straight line of a finite element. A pure numerical Kelvin/Voigt like rheological model capable of nonlinear large deformations is originally proposed here. It is numerically solved along time to accomplish the damping parameters of the device. Examples are solved to validate the formulation and to show the practical possibilities of the proposed technique
DOI: 10.6084/m9.figshare.14324896.v1
title: Effects of Partial Edge Loading and Fibre Configuration on Vibration and Buckling Characteristics of Stiffened Composite Plates

description: Abstract In this work, the influence of uniaxial and biaxial partial edge loads on buckling and vibration characteristics of stiffened laminated plates is examined by using finite element method. As the initial pre-buckling stress distributions within an element are highly non-uniform in nature for a given loading and edge conditions, the critical loads are evaluated by dynamic approach. Towards this, a nine-node heterosis plate element and a compatible three-node beam element are developed by employing the effect of shear deformation for both the plate and the stiffeners respectively. In the structural modeling, the plate and the stiffener elements are treated separately, and then the displacement compatibility is maintained between them by using a transformation matrix. Effect of different parameters such as loaded edge width, position of loads, boundary conditions, ply-orientations and stiffener factors are considered in this study. Buckling results show that the uniaxial loaded stiffened plate with around (+30º/-30º)2 layup can withstand higher load irrespective of boundary conditions and loading patterns, whereas the maximum load resisting layup for the bi-axially loaded stiffened plate is purely dependent on edge conditions and loading patterns.
DOI: 10.6084/m9.figshare.14324746.v1
title: Aerothermoelastic Analysis of Functionally Graded Plates Using Generalized Differential Quadrature Method

description: Abstract In the present paper, the aerothermoelastic behavior of Functionally Graded (FG) plates under supersonic airflow is investigated using Generalized Differential Quadrature Method (GDQM). The structural model is considered based on the classical plate theory and the von Karman strain-displacement relations are utilized to involve the nonlinear behavior of the plate. To consider the supersonic aerodynamic loads on the plate, the first order piston theory is applied. The material properties of the FG panel are assumed to be temperature independent and alter in the thickness direction according to a power law distribution. The temperature distribution on the surface of the plate is assumed to be constant and in the thickness direction is obtained by one-dimensional steady conductive heat transfer equation. The discretized governing equations via GDQM are solved by the fourth order Runge-Kutta method. Comparison of the obtained results with those available in literature confirms the accuracy and ability of the GDQM to perform the aerothermoelastic analysis of FG plates. Also, the effect of some important parameters such as Mach number, in-plane thermal load, plate aspect ratio and volume fraction index on the plate aerothermoelastic behavior is examined.
DOI: 10.6084/m9.figshare.14324623.v1
title: Pressure-Based and Potential-Based Differential Quadrature Procedures for Free Vibration of Circular Plates in Contact with Fluid

description: Abstract The differential quadrature method (DQM) has been so far applied to a wide variety of fluid and/or structural problems. The results of many researchers reveal that the DQM is computationally efficient and is applicable to a large class of boundary value problems. However, there is little information about its applications to fluid-structure interaction problems. Therefore, the purpose of this paper is to provide some information in this area and to develop procedures based on the DQM for the numerical solution of fluid-structure interaction problems. First, the governing partial differential equations of motion of the structure and fluid are discretized separately using the DQM. Then, by applying the boundary condition at fluid-structure interface, the governing eigenvalue equations of the coupled system are obtained which can then be solved for the eigenvalues of the system. The applicability of the proposed procedures is shown herein through the free vibration analysis of thin circular plates in contact with a cylindrical fluid-filled cavity. Issues related to the implementation of the regularity conditions at the center of the circular plate and the central line of the cylindrical cavity are addressed. Two new regularity conditions are proposed for the circular cylindrical fluid domain. The accuracy and efficiency of the proposed procedures are demonstrated by comparing the obtained results with those available in the literature. It is shown that highly accurate converged results can be obtained by the proposed procedures using a small number of grid points. Three new dimensionless parameters and variables are also introduced for the free vibration of the coupled system. The influences of these parameters on dynamic behavior of the system are studied.
DOI: 10.6084/m9.figshare.14325314.v1
title: Ballistic gelatin Lagrange Mooney-Rivlin material model as a substitute of bird in finite element bird strike case studies

description: Abstract Numerical simulation plays a crucial role in today’s aviation industry. Modern computers with the latest commercial FE codes have fueled the triumph of establishing simulation as a prerequisite of aerostructure part design from micro modeling of materials to large-scale structural analysis. In this current research paper, a Mooney-Rivlin material model of ballistic gelatin with Lagrange code is analyzed as a potential candidate for the computational bird model to simulate bird strike case studies. To investigate the practicability, the model is compared with other established Lagrange and SPH EOS models for both rigid and deformable body impacts along with experimental data found in the literature adopting explicit solver Ansys Autodyn. Despite some discrepancies found during rigid body impacts, deformable plate impacts confirm the robustness of the model with significantly faster computation time. Besides, the biggest criticism of the Lagrange model, mesh distortion problem as fluid during bird strike case studies is efficiently tackled by adopting the node erosion algorithm as an effective technique to solve Lagrange bird models without affecting the outcome of the solutions.
DOI: 10.6084/m9.figshare.14325314
title: Ballistic gelatin Lagrange Mooney-Rivlin material model as a substitute of bird in finite element bird strike case studies

description: Abstract Numerical simulation plays a crucial role in today’s aviation industry. Modern computers with the latest commercial FE codes have fueled the triumph of establishing simulation as a prerequisite of aerostructure part design from micro modeling of materials to large-scale structural analysis. In this current research paper, a Mooney-Rivlin material model of ballistic gelatin with Lagrange code is analyzed as a potential candidate for the computational bird model to simulate bird strike case studies. To investigate the practicability, the model is compared with other established Lagrange and SPH EOS models for both rigid and deformable body impacts along with experimental data found in the literature adopting explicit solver Ansys Autodyn. Despite some discrepancies found during rigid body impacts, deformable plate impacts confirm the robustness of the model with significantly faster computation time. Besides, the biggest criticism of the Lagrange model, mesh distortion problem as fluid during bird strike case studies is efficiently tackled by adopting the node erosion algorithm as an effective technique to solve Lagrange bird models without affecting the outcome of the solutions.
DOI: 10.6084/m9.figshare.14324613.v1
title: Bending, Vibration and Buckling of Laminated Composite Plates Using a Simple Four Variable Plate Theory

description: Abstract In the present study, a simple trigonometric shear deformation theory is applied for the bending, buckling and free vibration of cross-ply laminated composite plates. The theory involves four unknown variables which are five in first order shear deformation theory or any other higher order theories. The in-plane displacement field uses sinusoidal function in terms of thickness co-ordinate to include the shear deformation effect. The transverse displacement includes bending and shear components. The present theory satisfies the zero shear stress conditions at top and bottom surfaces of plates without using shear correction factor. Equations of motion associated with the present theory are obtained using the dynamic version of virtual work principle. A closed form solution is obtained using double trigonometric series suggested by Navier. The displacements, stresses, critical buckling loads and natural frequencies obtained using present theory are compared with previously published results and found to agree well with those.