scholarly journals Effect of floating axial holder on oscillating cold forging of spline shaft

2018 ◽  
Vol 249 ◽  
pp. 02001
Author(s):  
N Y Ben ◽  
Q Zhang ◽  
M G Lee
Keyword(s):  
Material Flow ◽  
Elastic Recovery ◽  
Nonlinear Function ◽  
Material Model ◽  
Cold Forging ◽  
Fe Model ◽  
Tooth Shape ◽  
Constitutive Material Model ◽  
Spline Shaft ◽  
Forming Defects

Oscillating technique is applied into the axial forging process of spline shaft to decrease the forming load and improve the quality of products. A floating axial holder with dwell force is designed to control the material flow. The influences of the floating axial holder have been analysed by finite element (FE) simulation and then verified by experiments. A FE model that considers material property change, elastic recovery and elastoplastic friction was built. The constitutive material model, which is mainly composed of variable elastic modulus and rate-dependent hardening, was used to simulate changes in material properties. Results showed that material flow was improved by decreasing dwell force. Tooth shape can be controlled by changing the dwell force of floating axial holder. The nonlinear function between addendum circle diameter and dwell force has been found. Hence, an optimal value of dwell force was determined considering the forming force, forming defects and tooth shape. Based on the simulating results, the optimal and irrational parameters of dwell force and frequency have been compared in the experiments. The typical defects of flash and accumulation can be eliminated by using the floating axial holder with optimal parameters.

scholarly journals Cold Forging Effect on the Microstructure of Motorbike Shock Absorbers Fabricated by Tube Forming in a Closed Die

2021 ◽  
Vol 11 (5) ◽  
pp. 2142
Author(s):  
Trung-Kien Le ◽  
Tuan-Anh Bui
Keyword(s):  
Material Flow ◽  
Cold Forging ◽  
Technological Parameters ◽  
Forming Process ◽  
Tube Forming ◽  
Shock Absorbers ◽  
Thin Walled Tube ◽  
Thin Walled ◽  
Quality Of Products ◽  
Forming Defects

Motorbike shock absorbers made with a closed die employ a tube-forming process that is more sensitive than that of a solid billet, because the tube is usually too thin-walled to conserve material. During tube forming, defects such as folding and cracking occur due to unstable tube forming and abnormal material flow. It is therefore essential to understand the relationship between the appearance of defects and the number of forming steps to optimize technological parameters. Based on both finite element method (FEM) simulations and microstructural observations, we demonstrate the important role of the number and methodology of the forming steps on the material flow, defects, and metal fiber anisotropy of motorbike shock absorbers formed from a thin-walled tube. We find limits of the thickness and height ratios of the tube that must be held in order to avoid defects. Our study provides an important guide to workpiece and processing design that can improve the forming quality of products using tube forming.

scholarly journals NUMERICAL SIMULATION OF THE BLAST-RESISTANT RESPONSE OF ULTRAHIGH-PERFORMANCE CONCRETE STRUCTURAL MEMBERS

2019 ◽  
Vol 25 (6) ◽  
pp. 587-598 ◽  
Author(s):  
Hor Yin ◽  
Kazutaka Shirai ◽  
Wee Teo
Keyword(s):  
Damage Model ◽  
High Strength ◽  
Material Model ◽  
Experimental Results ◽  
Fe Model ◽  
Structural Members ◽  
Fe Modelling ◽  
Constitutive Material Model ◽  
Concrete Damage ◽  
Explicit Solver

This paper presents the blast responses of ultrahigh-performance concrete (UHPC) structural members obtained using finite element (FE) modelling. The FE model was developed using LS-DYNA with an explicit solver. In the FE simulation, the concrete damage model, which is a plasticity-based constitutive material model, was employed for the concrete material. The simulation results were verified against previous experimental results available in the literature and were shown to be in good agreement with the experimental results. In addition, the developed FE model was implemented in a parametric study by varying the blast weight charges. The numerical results for UHPC members were compared with those for conventional reinforced concrete (RC) members. The numerical responses, such as the maximum deflections, deflected shapes, and damage patterns, of the UHPC members subjected to blast loading were significantly better performance than those of the RC members as a result of the high strength and ductile capacity of UHPC.

Improving the Fatigue Resistance Of Cold Forging Tools by Fe Simulation and Computer Aided Die Shape Optimization

1992 ◽  
Vol 206 (2) ◽  
pp. 143-150 ◽  
Author(s):  
M Geiger ◽  
M Hänsel ◽  
T Rebhan
Keyword(s):  
Finite Element ◽  
Fatigue Resistance ◽  
Process Simulation ◽  
Material Flow ◽  
Cold Forging ◽  
Material Research ◽  
Fe Model ◽  
Tool Failure ◽  
Friction Forces ◽  
Computer Aided

It is the intention of the present article to point out a new method for computer aided tool optimization as part of computer integrated tool manufacturing. Based on the results of finite element (FE) analysis and subsequent tool failure simulation, it is possible to optimize the FE model of a tool already at the stage of construction, in order to enhance the service life and process reliability. The permissible degree of freedom for any shape correction, of course, is mainly limited by constructive constraints of the tool and the properties of the material flow during the extrusion process. Thus the resulting optimized geometry has to he considered as a possible constructive alternative. However, analytical as well as practical solutions already show that a parabolical or elliptical curved surface contour, replacing a regular radius, not only improves the fatigue resistance but may have a positive influence on material flow behaviour, friction forces and resulting tool loads as well (1). The influence imposed on the material flow by the geometrical modification of the die shape will be clarified in future by the results of FE process simulation. A renewed simulation run, employing the optimized shape, may be conducted immediately after the optimization process. Along with current material research, the simulation of tool failure based on the finite element method (FEM) analysis of forging techniques (FE process simulation) therefore represents a promising direction for future developments (2–4).

scholarly journals Optimization of the Curved Metal Damper to Improve Structural Energy Dissipation Capacity

Buildings ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 67
Author(s):  
Young-Chan Kim ◽  
Seyed Javad Mortazavi ◽  
Alireza Farzampour ◽  
Jong-Wan Hu ◽  
Iman Mansouri ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Shape Optimization ◽  
Specific Area ◽  
Material Model ◽  
Optimization Techniques ◽  
Hysteretic Behavior ◽  
Design Parameters ◽  
Fe Model ◽  
Constitutive Material Model ◽  
Energy Dissipation Capacity

Structural curved metal dampers are implemented in various applications to mitigate the damages at a specific area efficiently. A stable and saturated hysteretic behavior for the in-plane direction is dependent on the shape of a curved-shaped damper. However, it has been experimentally shown that the hysteretic behavior in the conventional curved-shaped damper is unstable, mainly as a result of bi-directional deformations. Therefore, it is necessary to conduct shape optimization for curved dampers to enhance their hysteretic behavior and energy dissipation capability. In this study, the finite element (FE) model built in ABAQUS, is utilized to obtain optimal shape for the curved-shaped damper. The effectiveness of the model is checked by comparisons of the FE model and experimental results. The parameters for the optimization include the curved length and shape of the damper, and the improved approach is conducted by investigating the curved sections. In addition, the design parameters are represented by B-spline curves (to ensure enhanced system performance), regression analysis is implemented to derive optimization formulations considering energy dissipation, constitutive material model, and cumulative plastic strain. Results determine that the energy dissipation capacity of the curved steel damper could be improved by 32% using shape optimization techniques compared to the conventional dampers. Ultimately, the study proposes simple optimal shapes for further implementations in practical designs.

scholarly journals Identification of the LLDPE Constitutive Material Model for Energy Absorption in Impact Applications

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1537
Author(s):  
Luděk Hynčík ◽  
Petra Kochová ◽  
Jan Špička ◽  
Tomasz Bońkowski ◽  
Robert Cimrman ◽  
...  
Keyword(s):  
Strain Rate ◽  
Material Model ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Stress Strain ◽  
Rate Dependent ◽  
Constitutive Material Model ◽  
Principal Directions ◽  
Constitutive Material

Current industrial trends bring new challenges in energy absorbing systems. Polymer materials as the traditional packaging materials seem to be promising due to their low weight, structure, and production price. Based on the review, the linear low-density polyethylene (LLDPE) material was identified as the most promising material for absorbing impact energy. The current paper addresses the identification of the material parameters and the development of a constitutive material model to be used in future designs by virtual prototyping. The paper deals with the experimental measurement of the stress-strain relations of linear low-density polyethylene under static and dynamic loading. The quasi-static measurement was realized in two perpendicular principal directions and was supplemented by a test measurement in the 45° direction, i.e., exactly between the principal directions. The quasi-static stress-strain curves were analyzed as an initial step for dynamic strain rate-dependent material behavior. The dynamic response was tested in a drop tower using a spherical impactor hitting a flat material multi-layered specimen at two different energy levels. The strain rate-dependent material model was identified by optimizing the static material response obtained in the dynamic experiments. The material model was validated by the virtual reconstruction of the experiments and by comparing the numerical results to the experimental ones.

scholarly journals Flexural behavior of composite structural insulated panels with magnesium oxide board facings

2020 ◽  
Vol 20 (4) ◽  
Author(s):  
Łukasz Smakosz ◽  
Ireneusz Kreja ◽  
Zbigniew Pozorski
Keyword(s):  
Magnesium Oxide ◽  
Material Model ◽  
Expanded Polystyrene ◽  
Flexural Behavior ◽  
Joint Analysis ◽  
Model Parameters ◽  
Fe Model ◽  
Computational Results ◽  
Four Point Bending ◽  
Proposed Model

Abstract The current report is devoted to the flexural analysis of a composite structural insulated panel (CSIP) with magnesium oxide board facings and expanded polystyrene (EPS) core, that was recently introduced to the building industry. An advanced nonlinear FE model was created in the ABAQUS environment, able to simulate the CSIP’s flexural behavior in great detail. An original custom code procedure was developed, which allowed to include material bimodularity to significantly improve the accuracy of computational results and failure mode predictions. Material model parameters describing the nonlinear range were identified in a joint analysis of laboratory tests and their numerical simulations performed on CSIP beams of three different lengths subjected to three- and four-point bending. The model was validated by confronting computational results with experimental results for natural scale panels; a good correlation between the two results proved that the proposed model could effectively support the CSIP design process.

scholarly journals Modelling Texturised Cast Structures in the Forging of Superalloys

2011 ◽  
Vol 278 ◽  
pp. 210-215
Author(s):  
Jan Terhaar ◽  
Nikolaus Blaes ◽  
Dieter Bokelmann ◽  
Hendrik Schafstall
Keyword(s):  
Flow Stress ◽  
Material Flow ◽  
Cylindrical Specimen ◽  
Material Model ◽  
Growth Direction ◽  
Solidification Structure ◽  
Vacuum Arc ◽  
Correct Prediction ◽  
Dendrites Growth ◽  
Stress Dependency

The main objective of remelting processes commonly used in the production of super¬alloys is to obtain a columnar dendritic solidification structure throughout the whole ingot. Besides reduced microsegregation, this cast structure features a preferred orientation, which is depending on the primary dendrites’ growth direction and therefore closely related to the ingot’s pool shape. As a result, non-isotropic material behaviour can be observed during initial forging operations. Since the correct prediction of material flow is a prerequisite for the further analysis of forging processes by means of numerical simulation, the solidification texture’s influence on plastic flow was accounted for by the application of an anisotropic material model. The model according to Barlat was used to scale the flow stress with respect to the crystal orientations observed in the examination of vacuum arc remelted alloy 718, thereby considering the flow stress’ dependency on strain, strain rate and temperature. The parameters defining the material's anisotropy could be determined by the upsetting of cylindrical specimen from a remelted ingot.

Prediction of Defects in Multistage Cold Forging by Using Finite Element Method

2014 ◽  
Vol 622-623 ◽  
pp. 659-663 ◽  
Author(s):  
Fabio Bassan ◽  
Paolo Ferro ◽  
Franco Bonollo
Keyword(s):  
Radial Flow ◽  
Surface Defects ◽  
Plastic Instability ◽  
Cold Forging ◽  
Formation Mechanisms ◽  
Fe Model ◽  
Pipe Fitting ◽  
Tooling Design ◽  
Simulated Flow ◽  
Good Agreement

In this work, the formation mechanisms of surface defects in multistage cold forging of axisymmetrical parts have been studied through FEM simulations. As case history, the industrial production of an heating pipe fitting by cold forging has been analyzed. Based on simulated flow behaviour of material, several types of surface defects are identified and attributed to plastic instability of the work-material, inappropriate axial/radial flow ratio, excessive forming-pressure and uncorrect tooling design. The results of the FE model are finally compared with those obtained from real forging process and good agreement is observed.

scholarly journals Numerical Study on Surface Roughness Measurement Based on Nonlinear Ultrasonics in Through-Transmission and Pulse-Echo Modes

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4855
Author(s):  
Maodan Yuan ◽  
Anbang Dai ◽  
Lin Liao ◽  
Yan Chen ◽  
Xuanrong Ji
Keyword(s):  
Surface Roughness ◽  
Numerical Study ◽  
Material Model ◽  
Nonlinearity Parameter ◽  
Fe Model ◽  
Roughness Measurement ◽  
Monitoring Method ◽  
Surface Roughness Measurement ◽  
Nonlinear Ultrasonics ◽  
Pulse Echo

Ultrasonic is one of the well-known methods for surface roughness measurement, but small roughness will only lead to a subtle variation of transmission or reflection. To explore sensitive techniques for surfaces with small roughness, nonlinear ultrasonic measurement in through-transmission and pulse-echo modes was proposed and studied based on an effective unit-cell finite element (FE) model. Higher harmonic generation in solids was realized by applying the Murnaghan hyperelastic material model. This FE model was verified by comparing the absolute value of the nonlinearity parameter with the analytical solution. Then, random surfaces with different roughness values ranging from 0 μm to 200 μm were repeatedly generated and studied in the two modes. The through-transmission mode is very suitable to measure the surfaces with roughness as small as 3% of the wavelength. The pulse-echo mode is sensitive and effective to measure the surface roughness ranging from 0.78% to 5.47% of the wavelength. This study offers a potential nondestructive testing and monitoring method for the interfaces or inner surfaces of the in-service structures.

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