Modeling material failure with a vectorized routine

The computational aspects of modelling material failure in structural wood members are presented with particular reference to vector processing aspects. Wood members are considered to be highly orthotropic, inhomogeneous, and discontinuous due to the complex microstructure of wood material and the presence of natural growth characteristics such as knots, cracks and cross grain in wood members. The simulation of strength behavior of wood members is accomplished through the use of a special purpose finite element/fracture mechanics routine, program STARW (Strength Analysis Routine for Wood). Program STARW employs quadratic finite elements combined with singular crack tip elements in a finite element mesh. Vector processing techniques are employed in mesh generation, stiffness matrix formation, simultaneous equation solution, and material failure calculations. The paper addresses these techniques along with the time and effort requirements needed to convert existing finite element code to a vectorized version. Comparisons in execution time between vectorized and nonvectorized routines are provided

In-plane torsional stiffness in a macro-panel element for practical finite element modelling

Finite element (FE) analysis produces results, which, in most cases, gain in accuracy, as the size of the FE mesh is reduced. However, this is not necessarily the case when beam and shell element connections induce in-plane torsional effects in the shell. In such situations, shell elements either do not allow for an in-plane torsional stiffness, or, when present, the in-plane torsional stiffness is incorrectly affected by the sizes of the elements. To overcome this problem, we propose a macro- panel element that has fewer degrees of freedom, includes a new model for in-plane torsional stiffness, and produces results with sufficient accuracy to meet engineering requirements. The panel element is based on the principle of sub-structuring, i.e., the panel is meshed internally by smaller shell elements. As shown in the paper, the proposed panel element can be quite large, yet, it can give accurate analysis results. This work helps to overcome a common dilemma in practical use of finite element analysis, where finite element theory requires element sizes to be sufficiently small, but practical considerations suggest the use of large-size elements that simplify the modelling process and reduce excesses in generated results. A model built using macro-panel elements is equivalent to the model built using smaller shell elements, with the normal and shear stresses in the former being the same as the stresses in the finely meshed shell element model, We identify a number of performance benefits that become available as a consequence of modelling the shell elements at a higher level of abstraction

Electroplating Jig Design for Mild Steel Nut for Cobalt Alloy Plating

This partly ongoing research focuses on designing a stainless-steel jig holder for varied sizes of mild steel nuts for cobalt alloy plating, scaled to industry-level requirements for field testing. The chosen type of electroplating jig is rack plating. The modelling and analysis of the design were done using SolidWorks software, which included 3D design and finite element analysis. The result shows the strength of the jig holder is reliable for nut sizes ranging from M8 to M16. In conclusion, the jig holder performance has been successfully optimized based on the material and design chosen for its simulation. Keywords: Cobalt-Alloy Plating; Electroplating; Modelling; Finite Element Analysis eISSN: 2398-4287© 2022. The Authors. Published for AMER ABRA cE-Bs by e-International Publishing House, Ltd., UK. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians/Africans/Arabians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia. DO

Numerical Simulation of Projectile Impact on Mild Steel ArmourPlates using LS-DYNA: Part I: Validation

The paper describes  the simulation of impact of jacketed projectiles on steel armour plates usingexplicit finite element analysis as implemented in LS-DYNA. Validation of numerical modelling includesa comprehensive mesh convergence study leading to insights not previously reported in literature,using shell, solid, and axisymmetric elements for representing target plates. It is shown for a numberof cases that with a proper choice of contact algorithm, element size, and strain rate-dependent materialproperties, computed projectile residual velocities can match closely with corresponding test-basedvalues. The modelling requirements are arrived at by correlating against published test residual velocities1for variants of mild steel plates (designated as MS1, MS2 and MS3) of different thicknesses at impactvelocities in the range of ~820-870 m/s. Using the validated numerical procedure, a number of parametricstudies such as the effect of projectile shape and geometric aspect ratios as well as plate thickness onresidual velocity have been carried out and presented in Part II of the current paper

Modelling glacial erosional landform development

Glacial erosional systems exhibit a complex, highly scaledependent phenomenology. Some aspects of modelling the development of glacial erosional landforms in response to glacial erosional processes... acting over a wide range of scales are considered. The physics of ice at the glacier sole is discussed. A simple ice-water mixture theory is proposed. A method for finding the solution of the equations of motion of ice at the glacier sole based on the finite element velocities-pressure formulation is shown, which includes novel formulations for the sliding boundary condition, compression of ice and flow of water between ice and bedrock. These finite element formulations are used to simulate flows at the ice-rock interface. The use of the Laplace equation in simulating uni-axial flow is also considered, and further simulations are carried out using this equation. The results from these finite element simulations are used to consider erosional processes occurring at the glacier bed. The processes of abrasion are considered, and previous models are shown to be physically inconsistent. Cavitation, transiency and heterogeneity are shown to have an effect on clast-bed contact forces, and the local viscosity of ice is identified as being a further controlling variable on abrasion. These results are used to consider the likely development of hummocks of bedrock. A mass-balance analysis of basal debris is carried out and shown to have an important effect on erosional patterns. The equations describing the movement of a surface normal to itself are considered. Various solution techniques for these equations are tested, and requirements for the persistence of form under lowering are given. The modelling strategy used in this thesis is a nested hierarchy, with the various hierarchical levels corresponding to different scales. The effect of this hierarchisation on the modelling is discussed with respect to the generic properties of the systems, explanation and testability

Improvement of springback prediction in sheet metal forming

Finite element simulation of sheet metal forming is a well-established tool which is\ud used in industrial practice to evaluate geometrical defects caused by elastic springback.\ud Springback can be defined as an elastically-driven change of shape of the deformed\ud part upon removal of external loads. This phenomenon results in a deviation of the\ud real product geometry from that defined in the design phase and can cause significant\ud problems during assembly. To keep the product development time and manufacturing\ud costs low, finite element analysis aims to provide reliable information necessary for the\ud modification of tool and product geometry. Therefore, the accuracy of information\ud obtained in a numerical simulation of springback is essential for the product designers\ud and die makers.\ud This thesis deals with the improvement of numerical prediction of the springback\ud phenomenon in sheet metal forming. Modelling guidelines and advanced numerical\ud algorithms are presented that better satisfy industrial requirements for an accurate\ud simulation of springback

Box-Girder Bridges - Modelling and Analysis

The box-girder bridge has become very popular lately due to its serviceability, stability, and structural efficiency. The study of such a bridge requires analytical, experimental, or numerical methods. The structural behavior of the box-girder bridge is very complex and is quite cumbersome to be investigated by conventional methods. This paper presents a modelling process for the analysis of simply supported reinforced concrete (RC) box-girder bridges (straight, skew, curve, and skew-curved) using the finite element method under Indian loading conditions. This modelling process is developed on the basis of the Codal provisions of Indian Road Congress (IRC) 6:2017 and IRC 21:2000, and its implementation is quite simple as it avoids the cumbersome calculations and requires less time. Different values of the span, span-depth ratio, and the number of cells are considered to suit the requirements, and limiting criteria for stresses and deflection are checked. The static and free vibration analyses are carried out, and the results are compared to control the applicability of the proposed modelling process. The present modelling process is applied to analyse the RC box-girder bridges up to 50 m spans, and no erection procedure is included. However, one may follow the proposed modelling procedure for any box-girder bridge for its analysis

Finite element analysis of a novel aircraft seat against static certification requirements (CS25.561)

Extended abstractDue to the competitive nature of the airline industry and the desire to minimise aircraft weight, there is a continual drive to develop lightweight, reliable and more comfortable seating solutions, in particular, the development of a new generation slim economy seat. The key design challenge is to maximise the “living space” for the passenger, with strict adherence / compliance to Safety Regulations. This paper presents the analysis led design using finite element analysis of an innovative seat concept developed by BlueSKy Designers Limited, which has been acclaimed as “The most exciting development in aviation in over 30 years” and has won the company numerous awards. A generous angle of recline (40 degrees), movement of the “Seat Pan” along different gradients, and unique single “Forward Beam” design, distinguishes “Sleep Seat” from current generation seats. Compliance against Static Strength requirements (CS25.561) through a sequential model development approach was performed, in order to predict the stress induced in the primary seat structure, against static certification requirements. A critical design parameter is ensuring seat interface loads are below airline limits, which resulted in the inclusion of seat stud and track details in the finite element model. This stepwise and validated analysis framework, which includes mesh sensitivity studies, modelling of bolt-preload, representing bolted joints in FEA and obtaining a converged solution for non-linear FEA was essential in order to allow different concepts to be assessed virtually, thereby reducing development cycle time. The findings from this paper demonstrate that the seat is safe against CS 25.561

Analysis and design of AC induction motors with squirrel cage rotors

The traditional approach to modelling the AC induction motor revolves around the well-known equivalent T circuit model. In this approach, the direct connection from geometry to performance is suppressed. For better understanding of magnetic, electrical, and thermal behaviors, three lumped models based on the actual geometry are developed in this dissertation. Based on these lumped models, an iterative design model is also developed. In order to analyze and design induction motors, the relationships of basic motor variables to motor performance must be known. For determining the relationships, three new mathematical lumped models are developed. The magnetic model describes flux behavior. The electrical model, which is similar to the equivalent circuit model, is used to derive simple closed-form expressions of performance. The thermal model describes the effect of heat generation on temperature. The traditional approach of modelling the induction motor using the finite element analysis (FEA) is through the equivalent circuit model. Three new FEA methods are developed in this dissertation to calculate motor performance directly from the finite element field solution. The equivalent circuit model is no longer needed. The developed lumped models and FEA methods are applied to two commercial induction motors. Calculated performance is shown to closely match experimental results. The developed iterative design model is then utilized to design an induction motor for desired requirements. The motor is fabricated and calculated performance is also shown to closely match the experimental results

Finite element analysis of cellular structures subjected to wave loads

Cellular cofferdams are increasingly being used as permanent retaining walls, navigation or breakwater structures. When used as breakwaters, the metal fatigue can become a possible mode of failure for cellular structures due to the cyclic unbalanced lateral loads imposed by the wave action;This study was initiated as an investigation of the cell failures of the Calumet Harbor Breakwater structure in the South Chicago Harbor. The primary objective was the assessment of the interlock force fluctuations in the sheetpiles induced by the wave action on the structure;It has been well established that the conventional design methods for cellular structures have substantial shortcomings. These methods are usually overconservative and incapable of predicting deformations. In the past 15 years finite element method has been applied to analyze the cellular structures. The method provides the means to deal with soil-structure interaction problem, loading and geometric irregularities, as well as behavioral complexities of the materials. Past finite element work consisted of two-dimensional model versions. Each of these models require certain assumptions and simplifications regarding loads and geometry and can provide only specific information. Three-dimensional modelling can eliminate these drawbacks at the cost of complex and tedious modelling work and considerable increases in computation time and memory requirements;The Calumet Harbor Breakwater structure was analyzed using two-dimensional vertical slide and three-dimensional finite element models in parallel to evaluate the performances on a comparative basis. The analysis consisted of three main sequential stages: (1) simulation of the construction, (2) simulation of the permanent cumulative wave load effects on the structural condition of the breakwater, (3) wave load analysis;The analysis results showed that the model predictions regarding the interlock forces, displacements and lateral pressures were consistent in the construction simulation stage. However, the differences became more predominant under the increased loading in the second and third stages. In the second stage, the analysis results confirmed that the permanent effects of the wave loads alter the structural state of the breakwater considerably. Regarding the wave load analysis, three-dimensional model predictions resulted in a better agreement with the field recorded data