scholarly journals Evaluation of Weld Homogenization Schemes Based on Plastic Loading of Single Edge Notched Tension (SE(T)) Tests

2017 ◽  
Author(s):  
Sameera Naib ◽  
Wim De Waele ◽  
Stijn Hertelé
Keyword(s):  
Base Metal ◽  
Structural Integrity ◽  
Structural Response ◽  
Tensile Tests ◽  
Critical Assessment ◽  
Analysis Procedure ◽  
Single Edge ◽  
Weld Region ◽  
Weld Defect ◽  
Plastic Analysis

Engineering Critical Assessment (ECA) of welds is the process of predicting the structural integrity of a structure in the presence of a weld defect under specified loading conditions. Standardized ECA techniques consider the weld to be equal in properties when compared with base metal or use the concept of ‘strength mismatch’ to distinguish the weld from the base metal. In both cases, the weld region is homogeneous. This is a severe approximation from reality, as welds show complex strength heterogeneity patterns. The authors are concerned with techniques to simplify welds in such way that the structural response of the weld is similar to that of the idealized, homogeneous weld. Two approaches are considered: (a) integrating properties along assumed slip lines originating from the defect tip, and (b) assigning All Weld Metal Tensile Tests (AWMTT) to the entire weld region. A plastic analysis procedure suggested by the ASME BP&V code (‘Twice Elastic Slope method’) is adopted to estimate Plastic Load, whose values are compared for the heterogeneous and equivalent homogeneous welds. Finite Element (FE) simulations were performed for Single Edge notched Tensile (SE(T)) specimens. The results put forward the possibilities of weld homogenization while showing its limitations. This will assist in further improvement of weld ECA.

Influence of Rotary Friction Welding Parameters on Tensile Strength and Length of TMAZ of Dissimilar Welded Joints from 32G2 and 40KhN Steels

2021 ◽  
Vol 410 ◽  
pp. 299-305
Author(s):  
Artem S. Atamashkin ◽  
Elena Y. Priymak ◽  
Elena A. Kuzmina
Keyword(s):  
Tensile Strength ◽  
Base Metal ◽  
Process Parameters ◽  
Welded Joints ◽  
Friction Welding ◽  
Tensile Tests ◽  
Welding Parameters ◽  
Rotary Friction Welding ◽  
Study Results ◽  
Friction Pressure

In this work, pipe billets with a diameter of 73 mm and a wall thickness of 9 mm from steels 32G2 and 40KhN are friction welded with an aim to optimize the process parameters. The friction pressure, the forging pressure and the length of the fusion varied. After the implementation of various welding modes, tensile tests and metallographic studies were carried out. The optimal welding parameters have been established, which make it possible to obtain tensile strength at the level of the 32G2 base metal. The study results of the microstructure and SEM fractographs after the optimal welding mode are presented.

scholarly journals The Influence of Layer Thickness on the Microstructure and Mechanical Properties of M300 Maraging Steel Additively Manufactured by LENS® Technology

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 603
Author(s):  
Natalia Rońda ◽  
Krzysztof Grzelak ◽  
Marek Polański ◽  
Julita Dworecka-Wójcik
Keyword(s):  
Mechanical Properties ◽  
Layer Thickness ◽  
Maraging Steel ◽  
Structural Integrity ◽  
Tensile Tests ◽  
Dendritic Microstructure ◽  
Fine Grained ◽  
Laser Engineered Net Shaping ◽  
Microstructure And Mechanical Properties ◽  
Net Shaping

This work investigates the effect of layer thickness on the microstructure and mechanical properties of M300 maraging steel produced by Laser Engineered Net Shaping (LENS®) technique. The microstructure was characterized using light microscopy (LM) and scanning electron microscopy (SEM). The mechanical properties were characterized by tensile tests and microhardness measurements. The porosity and mechanical properties were found to be highly dependent on the layer thickness. Increasing the layer thickness increased the porosity of the manufactured parts while degrading their mechanical properties. Moreover, etched samples revealed a fine cellular dendritic microstructure; decreasing the layer thickness caused the microstructure to become fine-grained. Tests showed that for samples manufactured with the chosen laser power, a layer thickness of more than 0.75 mm is too high to maintain the structural integrity of the deposited material.

scholarly journals ARMOUR UNIT STRUCTURAL RESPONSE - A PARAMETRIC STUDY

1988 ◽  
Vol 1 (21) ◽  
pp. 176
Author(s):  
C. David Anglin ◽  
William F. Baird ◽  
Etienne P.D. Mansard ◽  
R. Douglas Scott ◽  
David J. Turcke
Keyword(s):  
Wave Height ◽  
Parametric Study ◽  
Structural Integrity ◽  
Design Procedure ◽  
Structural Response ◽  
Design Parameters ◽  
Coastal Structures ◽  
Log Normal ◽  
Wave Induced ◽  
Hydraulic Stability

There is a general lack of knowledge regarding the nature and magnitude of loads acting on armour units used for the protection of rubblemound coastal structures. Thus, a comprehensive design procedure incorporating both the hydraulic stability and the structural integrity of the armour units does not exist. This paper presents the results of a detailed parametric study of the structural response of armour units to wave-induced loading in a physical breakwater model. The effect of the following design parameters is investigated: breakwater slope, armour unit location, wave period and wave height. This research has made a number of significant contributions towards the development of a comprehensive design procedure for concrete armour units. It has identified a linear relationship between the wave-induced stress in the armour units and the incident wave height. In addition, it has shown that the conditional probability of waveinduced stress given wave height can be estimated by a log-normal distribution. Finally, a preliminary design chart has been developed which incorporates both the structural integrity and the hydraulic stability of the armour units.

Effect of Loading Rate on Tensile Properties of Automotive Steel Sheet

2013 ◽  
Vol 690-693 ◽  
pp. 211-217
Author(s):  
Jin Gui Qin ◽  
Fang Yun Lu ◽  
Yu Liang Lin ◽  
Xue Jun Wen
Keyword(s):  
Strain Rate ◽  
Testing Machine ◽  
Structural Response ◽  
Tensile Tests ◽  
Dynamic Tests ◽  
Static Tests ◽  
Split Hopkinson Tensile Bar ◽  
Axial Tensile ◽  
Static Tensile ◽  
Cook Model

Results of uni-axial tensile loading of three automotive steels at different strain rates (0.0011–3200s-1) are reported here. Quasi-static tensile tests were performed under the strain rate of 1.1×10-3 s-1 using an electromechanical universal testing machine, whereas dynamic tests were carried out under the strain rate in the range of 1100 to 3200 s-1 using a Split Hopkinson Tensile Bar apparatus. Based on the experimental results, the material parameters of widely used Johnson–Cook model which described the strain rate and temperature-dependent of mechanical behaviour were determined. The experiments show that strain-rate hardening is superior to thermal softening: yield stresses, tensile strength, deformation, and energy dissipation increase with the strain rate from quasi-static tests to dynamic tests. The Johnson–Cook model can describe the behaviour of these steels and provides the opportunity to study the material and structural response.

scholarly journals Fish Cells, a new zero Poisson’s ratio metamaterial—Part I: Design and experiment

2020 ◽  
Vol 31 (13) ◽  
pp. 1617-1637
Author(s):  
Mohammad Naghavi Zadeh ◽  
Iman Dayyani ◽  
Mehdi Yasaee
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Poisson’S Ratio ◽  
Structural Integrity ◽  
Structural Response ◽  
Poisson's Ratio ◽  
Experimental Investigations ◽  
Fish Cells ◽  
Force Displacement ◽  
Model Approach

A novel cellular mechanical metamaterial called Fish Cells that exhibits zero Poisson’s ratio in both orthogonal in-plane directions is proposed. Homogenization study on the Fish Cells tessellation is conducted and substantially zero Poisson’s ratio behavior in a homogenized tessellation is shown by numerical analysis. Experimental investigations are performed to validate the zero Poisson’s ratio feature of the metamaterial and obtain force–displacement response of the metamaterial in elastic and plastic zone. A detailed discussion about the effect of the numerical model approach and joints on the structural response of the metamaterial is presented. Morphing skin is a potential application for Fish Cells metamaterial because of the integration benefits of zero Poisson’s ratio design. The structural integrity of the Fish Cells is investigated by studying the stiffness augmentation under tension and in presence of constraints on transverse edges. Finally, geometrical enhancements for improved integrity of the Fish Cells are presented that result in substantially zero stiffness augmentation required for morphing skins.

scholarly journals Spark Plasma Diffusion Bonding of TiAl/Ti2AlNb with Ti as Interlayer

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3300
Author(s):  
Boxian Zhang ◽  
Chunhuan Chen ◽  
Jianchao He ◽  
Jinbao Hou ◽  
Lu Chai ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Base Metal ◽  
Diffusion Bonding ◽  
Energy Dispersive Spectrometer ◽  
Tensile Tests ◽  
Slow Cooling ◽  
Ti2alnb Alloy ◽  
Heat Treated ◽  
Plasma Diffusion ◽  
Spark Plasma

To solve the problem of poor weldability between TiAl-based and Ti2AlNb-based alloys, spark plasma diffusion bonding was employed to join a TiAl alloy and a Ti2AlNb alloy with a pure Ti foil as interlayer at 950 °C/10 KN/60 min. After welding, slow cooling was carried out at a rate of 5 °C/min, followed by homogenization at 800 °C for 24 h. The microstructural evolution and elemental migration of the joint were analyzed via a scanning electron microscope equipped with an energy dispersive spectrometer, while the mechanical properties of the joint were assessed via microhardness and tensile tests. The results show that the spark plasma diffusion bonding formed a joint of TiAl/Ti/Ti2AlNb without microcracks or microvoids, while also effectively protecting the base metal. Before heat treatment, the maximum hardness value (401 HV) appeared at the Ti2AlNb/Ti interface, while the minimum hardness value (281 HV) occurred in the TiAl base metal. The tensile strength of the heat-treated joint at room temperature was measured to be up to 454 MPa, with a brittle fracture occurring in the interlayer. The tensile strength of the joint at 650 °C was measured to be up to 538 MPa, with intergranular cracks occurring in the TiAl base metal.

scholarly journals Assessment of Structural Performance and Integrity for Vibration-based Energy Harvester in Frequency Domain

Electronics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 357
Author(s):  
Ji-Won Jin ◽  
Ki-Weon Kang
Keyword(s):  
Frequency Domain ◽  
Natural Frequency ◽  
Production Efficiency ◽  
Performance Test ◽  
Energy Harvester ◽  
Structural Integrity ◽  
Structural Response ◽  
Structural Performance ◽  
Railway Vehicle ◽  
Response Analysis

A vibration-based energy harvester (VEH) utilizes vibrations originated from various structures and specifically maximizes the displacement of its moving parts, using the resonance between the frequency of external vibration loads from the structure and the natural frequency of VEH to improve power production efficiency. This study presents the procedure to evaluate the structural performance and structural integrity of VEH utilized in a railway vehicle under frequency domain. First of all, a structural performance test was performed to identify the natural frequency and assess the structural response in frequency domain. Then, the static structural analysis was carried out using FE analysis to investigate the failure critical locations (FCLs) and effect of resonance. Finally, we conducted a frequency response analysis to identify the structural response and investigate the structural integrity in frequency domain. Based on these results, the authors assessed the structural performance and integrity of VEHs in two versions.

scholarly journals Monitoring of reinforced concrete short ties with the acoustic emission technique

2019 ◽  
Vol 281 ◽  
pp. 04001
Author(s):  
Djillali Mezhoud ◽  
Jacqueline Saliba
Keyword(s):  
Acoustic Emission ◽  
Reinforced Concrete ◽  
Structural Integrity ◽  
Tensile Tests ◽  
Average Frequency ◽  
Rc Structures ◽  
Surrounding Matrix ◽  
High Adhesion ◽  
Damage Process ◽  
Different Characteristics

Cracking in Reinforced Concrete (RC) structures may impact their durability and their structural integrity. Cracking is mainly influenced by stress distribution along the interface between steel and concrete. Thus, quantitative evaluation of steel-concrete bond, which is responsible of transferring load from steel bar to the surrounding matrix, and its effect on fracture properties is of major important. An experimental investigation on RC ties is reported in this paper. Tensile tests have been conducted on cubic specimens with different high adhesion reinforcement diameters. Those tests have been monitored continuously using the Acoustic Emission (AE) technique for a better evaluation of the damage process. The results show a good correlation between the load and the AE activity. AE signals with different characteristics have been observed during the different fracture stages. Parameters such as duration and energy increased with the loading level and can be used as indicators to detect the macrocracking of concrete. A parametric analysis is performed between average frequency and RA value. Ib-value of AE hits has been also investigated and decreases to 0.12 prior to the first macro crack.

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