Experimental and numerical investigation of hybrid laser arc welding process and the influence of welding sequence on the manufacture of stiffened flat panels

La soldadura por arco láser híbrido (HLAW) ha atraído cada vez más atención tanto de la industria como de los laboratorios académicos por su alta eficiencia y calidad de soldadura. El objetivo del presente artículo es desarrollar un método de elementos finitos no lineal para predecir la deflexión inducida por la soldadura y la tensión residual de un panel rígido a escala semiindustrial, utilizando un nuevo modelo de fuente de calor. La nueva fuente de calor híbrida consiste en un modelo matemático de doble elipsoide de Goldak que representa la fuente del arco, combinado con un modelo matemático gaussiano de cono truncado para simular la fuente láser. Para ello, se ha desarrollado un modelo de elementos finitos termoelástico-plástico acoplado tridimensional con ABAQUS utilizando una subrutina numérica adicional de DFLUX escrita en el lenguaje de programación Fortran para simular las distribuciones volumétricas de flujo de calor del proceso HLAW. El método de elementos finitos (FEM) se verifica mediante comparación con mediciones experimentales de muestras de acero naval EH36 de pequeña escala con uniones en T, en configuración a tope en posición de soldadura 2F, soldadas en posición horizontal con penetración total mediante un proceso híbrido de soldadura por arco láser (HLAW). Se observa una buena concordancia entre los resultados numéricos y las mediciones experimentales, lo que confirma que el modelo desarrollado en el presente artículo se puede utilizar eficazmente para predecir el comportamiento de deformación de las estructuras de rigidizadores durante la construcción naval. También se ha estudiado el efecto del cambio de secuencia de soldadura en el panel rígido a escala semiindustrial. Se han investigado cuatro secuencias de soldadura diferentes (SEQ 1,2,3 y 4), para elegir la mejor secuencia de soldadura en cuanto a la magnitud y distribución de las imperfecciones de soldadura (deflexión y tensión residual). Cambiar la secuencia de soldadura tiene un efecto significativo en la distribución y magnitud de la deflexión vertical. Se concluye que la secuencia de soldadura juega un papel importante en la deformación de las estructuras. Un cambio de dirección en la sección media, en combinación con la alternancia de las trayectorias de soldadura entre dos refuerzos consecutivos, conduce a una disminución significativa de la distorsión. El modelo FEM desarrollado ha proporcionado resultados precisos, lo que demuestra que es aplicable para estimar la deformación y la tensión residual inducida por el proceso HLAW en estructuras de construcción naval más grandes. También se puede emplear para optimizar la secuencia de soldadura. La presente contribución forma parte de un proyecto de colaboración entre la Universidad de Cádiz y la Universidad de Alejandría, Egipto, coordinado por el solicitante (J.M. Sánchez Amaya), cuyo principal objetivo es profundizar en el conocimiento y aplicación de las simulaciones FEM a procesos de soldadura. Este proyecto ha sido posible gracias a la financiación, por parte de la Comisión de la Unión Europea, de la beca de programa Erasmus + KA107, que ha permitido cubrir los gastos del viaje de Ahmed Hammad a la UCA. El solicitante (J.M. Sánchez Amaya) ha realizado las siguientes actividades del manuscrito: responsable y coordinador del conjunto de actividades de la colaboración; comparativa y análisis de resultados de las soldaduras HLAW; análisis y discusión de resultados del artículo; y revisión inicial y final del manuscrito

Lap Joint on St.37 Steel Plate with Friction Welding Clamping Method

Friction stir (FW) welding is a relatively fresh method that was created and has been continually refined and adapted to industrial applications due to its benefits. This approach for solid-state joining entails connecting the components at a temperature below their melting point and then heating them up. Clamp joint applications are widely used using external heating and hitting with high strength, but the clamped joints with the FW method are rarely done. The research studied the characteristic of clamped joints at various plate thicknesses using the FW method. In this study, 30 specimens were used in the form of a St.37 low carbon steel plate with a size of 50 mm x 100 mm and a thickness of 3 mm, 5 mm, and 9 mm, and several holes were made with a diameter of 5 mm. The plate was connected by 2 clamps, and 4 clamps then the FW method was conducted in a milling machine. The results indicate that the plates were connected well. The highest hardness value was 256.4 VHN on the FW of 9 mm plate. The microstructure is dominated by ferrite and a little pearlite phase. The largest shear force is 66.54 kN obtained at 4 clamps with a plate thickness of 9 mm, and the lowest is 13.46 kN, obtained at 2 clamps with a plate thickness of 3 mm

Recent Research and Developments in Cold-formed Steel Design and Construction

Golden Anniversary of the AISI Specification - The 1996 AISI Specification - A New AISI Cold-Formed Steel Design Manual - Design of Cold-Formed Steel Stiffened Elements with Multiple Longitudinal Intermediate Stiffeners - A Probablistic Examination of the Ultimate Strength of Cold-Formed Steel Elements - Effective Width of a Simple Edge-Stiffener Subjected to Stress Gradient - The Effects of Perforation Length on the Behaviour of Perforated Elements in Compression - Interaction of Flangel/Edge-Stiffened Cold-Formed Steel C-Sections - Cold-Formed Steel Flat Width Ratio Limits, d/t and d/w - Comparison of the Distortional Buckling Method for Flexural Members with Tests - Design of Thin-Walled Beams for Distortional Buckling - Comparison of Tests of Purlins With and Without Cleats - Determination of Purlin R-Factors Using a Non-Linear Analysis - Deflection Design of Cold-Formed RHS Steel Beams - Finite Element Analysis of Hollow Flange Beams with Web Stiffeners - Buckling Experiments on Hollow Flange Beams with Web Stiffeners - Flexural Strength of Cold-Formed Steel Panels Using Structural Grade 80 of A653 Steel - Experimental Research on the Behaviour of Combined Web Crippling and Bending of Steel Deck Sections - Design Models of Continuous Sandwich Panels - Structural Detailing of Openings in Sandwich Panels - Non-Linear Buckling Analysis of Thin-Walled Metal Columns - Effect of Bracing Stiffness on Buckling Strength of Cold-Formed Steel Columns - Structural Design Study on a Light- Gauge Steel Portal Frame with Cold-Formed Sigma Sections - Lower Cost Lightweight Cold-Formed Portal Frames - Strength and Stiffness Calculation Procedures for Composite Slabs - Strength of Headed Shear Studs in Cold-Formed Steel Deck - Towards a Numerical Procedure for Composite Slab Assessment - Moment Rotation Behavior for Concrete Filled SHS Column to Composite Beam Connection - Stability of Standing Seam Roof-Purlin Systems - Modeling of Cold-Formed Purlin-Sheeting Systems - Dynamic Performance of Light Gauge Steel Framed Shear Walls - Steel - The Clear Cut Alternative - Residential Applications of Cold-Formed Structural Members in Australia - A Study of the Effect of Cold Forming on the Yield Strength of Stainless Steel Type 304 - Hardness Test Approach - An Explicit Approach to Design of Stainless Steel Columns - The Strength of Partially Stiffened Stainless Steel Compression Members - Burst Strength of Type 304L Stainless Steel Tubes Subjected to Internal Pressure and External Forces - Additional Design Considerations for Bolted Connections - Shear Behavior of Self Drilling Screws Used in Low Ductility Steel - Performance of Self-Tapping Screws in Lap-Shear Metal-to-Metal Connections - Evaluation and Modelling of the Material Properties for Analysis of Cold-Formed Steel Sections - The Modulus of Elasticity of Steel Is it 200 GPa? - Geometric Imperfections and Residual Stresses for Use in the Analytical Modeling of Cold-Formed Steel Members - Cold-Formed Steel Sections Experimental Data Base - Cold-Formed Steel Design by Spreadsheet Progra

Predicting weld distortion in the design of automotive components

This project was set up in order to investigate whether it may be valid to use a simplified approach to weld distortion prediction in order to make an assessment of the distortions occurring in a welded structure. Distortion may manifest as problems associated with production, which increase costs and reduce profit. In order to validate the proposed prediction approach an experiment was developed to gain detailed information about distortions occurring in a series of simple welded joints. The joints and the parameters used for the experiment were based on the processes and applications of the case study company. The experiment was set up with the aim of evaluating the general magnitude and directions of distortion in bead on plate and butt weld joints to develop a database of distortion. The method for inspection of the experimental samples was to scan the parts using a 3D laser scanner to collect a detailed resolution point cloud that could be analysed. From the experimental results a number of key factors relating to the welded joints were found relating to material thickness, weld speed and penetration for the four different modes of distortion occurring. The experimental results were compared with the published data and equations presented by other authors, and some general agreements found, however, some differences were evident. In order for a designer to adjust the shape and form of a components design to counteract the distortions to achieve a nominal tolerance, based on these results, it was necessary to develop some new models specific to the materials and process variables of the case study company. Using an approach based on DoE software techniques, response surfaces for the experimental results were generated. This allowed equations to be developed for each distortion mode, which a designer could use to make predictions in the design phase to reduce risk from distortion

Recent Research and Developments in Cold-formed Steel Design and Construction

Unstiffened Elements - Some Interesting Features - Tests of Profiled Steel Decks with V-Stiffeners - Bending Strength of Beams with Non-Linear Analysis - Local and Distortional Buckling of Thin-Walled Beams - Design of C-Sections Against Deformational Lip Buckling - Lateral Buckling of Singly Symmetric Beams - Flexural Capacity of Discretely Braced C\u27s and Z\u27s - The Buckling Behaviour of Hollow Flange Beams - Experimental Investigations of I-Beams - Tests of Continuous Purlins Under Downwards Loading - Tests of Full-Scale Roofing Systems - Profiled Sheet Behaviour Under Concentrated Load - On Design of Profiled Sheets with Varying Cross Sections - Properties for Cellular Decks in Negative Bending - Contrasting Behaviour of Thin Steel Roof Claddings Under Simulated Cyclonic Wind Loading - New ASCE Standards for Cold-Formed Steel Deck Slabs - Composite Slabs Analyzed by Block Bending Test - Repeated Point Loading Tests on Composite Slabs - Thermal Shielding Near Intermediate Supports of Continuous Span Composite Slabs - Design of Channels Against Distortional Buckling - Distortional Buckling of Cold-Formed Steel Z-Section Columns - Shah Alam Sports Complex: Design and Construction of Unistrut Space-Frame Roof Structure - Flexibly Connected Thin-Walled Space Frame Stability - Test of a Full Scale Roof Truss - Down-Aisle Stability of Rack Structures - Racking Performance of Plasterboard-Clad Steel Stud Walls - An Experimental Study of Shear Wall Units - Some Applications of Generalized Beam Theory - Calibration of a Bending Model for Cold-Formed Sections - Recent Development in Cold-Formed Steel - The 1989 Edition ofthe Canadian Cold-Formed Steel Design Standard - Observations and Comments Pertaining to CAN/CSA-S136-M89 - Prediction of Corner Mechanical Properties for Stainless Steels Due to Cold Forming - Stainless Steel Tubular Beams - Tests and Design - The Lateral Torsional Buckling Strength of Cold-Formed Stainless Steel Lipped Channel Beams - Testing and Design of Bolted Connections in Cold-Formed Steel Sections - Behavior of Arc Spot Weld Connections in Tension - The Bi-Axial Behaviour of Shear Connectors in Composite Slabs and Beams - Influence of Deformed Metal Decking Composite Floors to Beam-Column Connections - Education in Cold-Formed Steel Structures - Lifelong Learning - Activities of the Center for Cold-Formed Steel Structure

Aeronautical engineering: A continuing bibliography with indexes (supplement 202)

This bibliography lists 447 reports, articles and other documents introduced into the NASA scientific and technical information system in June 1986

Large Space Antenna Systems Technology, part 1

A compilation of the unclassified papers presented at the NASA Conference on Large Space Antenna Systems Technology covers the following areas: systems, structures technology, control technology, electromagnetics, and space flight test and evaluation