scholarly journals Strain State in Metal Sheet Axisymmetric Stretching with Variable Initial Thickness: Numerical and Experimental Results

2021 ◽  
Vol 11 (17) ◽  
pp. 8265
Author(s):  
Gillo Giuliano ◽  
Wilma Polini
Keyword(s):  
Strain State ◽  
Thickness Distribution ◽  
Element Model ◽  
Alloy Sheet ◽  
Metal Sheet ◽  
Constant Thickness ◽  
Initial Thickness ◽  
Final Thickness ◽  
Stretching Process ◽  
Commercial Sheet

This work presents a finite element model to analyze the distribution of the strains due to an axisymmetric stretching of a metal sheet. The sheet is characterized by a variable initial thickness. The resulting strain state is compared with that of a sheet with a constant initial thickness. The results of the present study allow asserting that the distribution of strains in the sheet can be controlled by setting opportunely the trend of the sheet initial thickness. In this way, it is possible to see that, starting from a sheet with variable initial thickness, a lighter final product is obtained, whose final thickness distribution is more uniform than that of the product obtained from a classic stretching process that requires a sheet with constant initial thickness. Encouraging results from an experimental activity carried out on an AA6060 aluminum alloy sheet, whose trend of initial thicknesses was prepared by removing material from a commercial sheet with a constant thickness, allow us to note the good agreement with what was theoretically highlighted.

Superplastic Dome Forming of Machined Sheets

1999 ◽  
Vol 601 ◽  
Author(s):  
Nihat Akkus ◽  
Toshihiro Usugi ◽  
Masanori Kawahara ◽  
Ken-ichi Manabe ◽  
Hisashi Nishimura
Keyword(s):  
Constant Pressure ◽  
Thickness Distribution ◽  
Pressure Control ◽  
Control Mode ◽  
Constant Thickness ◽  
Al Alloy ◽  
Deformation Model ◽  
Final Thickness ◽  
Incremental Strain ◽  
Reverse Deformation

AbstractAn experimental work on the superplastic bulge forming of machined sheets is presented in this study. Unlike the previously employed incremental-iterative method, a reverse deformation model was used to estimate the initial thickness distribution of the machined sheets from which a constant final thickness can be obtained when the shape of the bulged sheet is hemisphere. The reverse deformation modci was obtained by modifying previously-known models, which were based on the axisymmetric membrane and the incremental strain theory.Bulge forming experiments were conducted on machined sheets of Al alloy, A5083, at about 530°C under constant pressure control mode. The result of this simulation to estimate the final constant thickness distribution agreed well with the experiment, and confirmed that the reverse deformation model can be successfully applied in optimizing the thickness distribution of the starting sheets in order to obtain the desired final thickness distribution of the free bulged hemispherical product.

Evaluation of Drawing Force and Thickness Distribution in the Deep-Drawing Process with Variable Blank-Holding

2015 ◽  
Vol 639 ◽  
pp. 33-40 ◽  
Author(s):  
Lucian Lazarescu ◽  
Ioan Nicodim ◽  
Dorel Banabic
Keyword(s):  
Finite Element ◽  
Deep Drawing ◽  
Thickness Distribution ◽  
Element Model ◽  
Alloy Sheet ◽  
Wall Thickening ◽  
Drawing Process ◽  
Drawing Force ◽  
Deep Drawing Process ◽  
Blank Holding Force

In the deep drawing process, the blank-holding force (BHF) is an important process parameter affecting the energy consumption and the successful production of parts. In the present work, both experiments and finite element simulations have been conducted to investigate the influence of constant and time variable BHF on drawing force (DF) and thickness distribution in the deep drawing process of cylindrical and square cups. A finite element model was developed in the AutoForm software and validated with experiments. The developed model has been used for the simulation of deep drawing process of AA6016-T4 aluminum alloy sheet. The experimental and numerical results show that, using a variable instead of a constant BHF, the DF can be decreased in the expense of wall thickening.

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

MODELING OF THE STRESS-STRAIN STATE OF A TRANSPORT TUNNEL UNDER LOAD AS A MEASURE TO REDUCE OPERATIONAL RISKS TO TRANSPORTATION FACILITIES

2020 ◽  
Vol 3 (8) ◽  
pp. 28-34
Author(s):  
N. V. IVANITSKAYA ◽  
◽  
A. K. BAYBULOV ◽  
M. V. SAFRONCHUK ◽  
◽  
...  
Keyword(s):  
Strain State ◽  
Moving Load ◽  
Element Model ◽  
Transport Infrastructure ◽  
Design Stage ◽  
Surface Load ◽  
Stress Strain ◽  
Stress Strain State ◽  
Operational Risks ◽  
Von Mises

In many countries economic policy has been paying increasing attention to the modernization and development of transport infrastructure as a measure of macroeconomic stimulation. Tunnels as an important component of transport infrastructure save a lot of logistical costs. It stimulates increasing freight and passenger traffic as well as the risks of the consequences of unforeseen overloads. The objective of the paper is to suggest the way to reduce operational risks of unforeseen moving load by modeling of the stress-strain state of a transport tunnel under growing load for different conditions and geophysical parameters. The article presents the results of a study of the stress-strain state (SSS) of a transport tunnel exposed to a mobile surface load. Numerical experiments carried out in the ANSYS software package made it possible to obtain diagrams showing the distribution of equivalent stresses (von Mises – stresses) according to the finite element model of the tunnel. The research results give grounds to assert that from external factors the stress state of the tunnel is mainly influenced by the distance to the moving load. The results obtained make it possible to predict in advance the parameters of the stress-strain state in the near-contour area of the tunnel and use the results in the subsequent design of underground facilities, as well as to increase their reliability and operational safety. This investigation gives an opportunity not only to reduce operational risks at the design stage, but to choose an optimal balance between investigation costs and benefits of safety usage period prolongation.

scholarly journals Effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Niksa Mohammadi Bagheri ◽  
Mahmoud Kadkhodaei ◽  
Shiva Pirhadi ◽  
Peiman Mosaddegh
Keyword(s):  
Clinical Data ◽  
Three Dimensional ◽  
Element Model ◽  
Von Mises Stress ◽  
Patient Specific ◽  
Average Error ◽  
Constant Thickness ◽  
Arc Length ◽  
Implementation Techniques ◽  
Von Mises

AbstractThe implementation of intracorneal ring segments (ICRS) is one of the successfully applied refractive operations for the treatment of keratoconus (kc) progression. The different selection of ICRS types along with the surgical implementation techniques can significantly affect surgical outcomes. Thus, this study aimed to investigate the influence of ICRS implementation techniques and design on the postoperative biomechanical state and keratometry results. The clinical data of three patients with different stages and patterns of keratoconus were assessed to develop a three-dimensional (3D) patient-specific finite-element model (FEM) of the keratoconic cornea. For each patient, the exact surgery procedure definitions were interpreted in the step-by-step FEM. Then, seven surgical scenarios, including different ICRS designs (complete and incomplete segment), with two surgical implementation methods (tunnel incision and lamellar pocket cut), were simulated. The pre- and postoperative predicted results of FEM were validated with the corresponding clinical data. For the pre- and postoperative results, the average error of 0.4% and 3.7% for the mean keratometry value ($$\text {K}_{\text{mean}}$$ K mean ) were predicted. Furthermore, the difference in induced flattening effects was negligible for three ICRS types (KeraRing segment with arc-length of 355, 320, and two separate 160) of equal thickness. In contrast, the single and double progressive thickness of KeraRing 160 caused a significantly lower flattening effect compared to the same type with constant thickness. The observations indicated that the greater the segment thickness and arc-length, the lower the induced mean keratometry values. While the application of the tunnel incision method resulted in a lower $$\text {K}_{\text{mean}}$$ K mean value for moderate and advanced KC, the induced maximum Von Mises stress on the postoperative cornea exceeded the induced maximum stress on the cornea more than two to five times compared to the pocket incision and the preoperative state of the cornea. In particular, an asymmetric regional Von Mises stress on the corneal surface was generated with a progressive ICRS thickness. These findings could be an early biomechanical sign for a later corneal instability and ICRS migration. The developed methodology provided a platform to personalize ICRS refractive surgery with regard to the patient’s keratoconus stage in order to facilitate the efficiency and biomechanical stability of the surgery.

scholarly journals On the issue of dynamic loading of supporting structures of special wheeled chassis

2019 ◽  
pp. 73-83
Author(s):  
V. I. Tarichko ◽  
P. I. Shalupina
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Loading ◽  
Strain State ◽  
Element Model ◽  
Stress Strain ◽  
Full Size ◽  
Equivalent Stresses ◽  
Stress Strain State ◽  
Supporting Structures

The paper focuses on a method for assessing the dynamic loading of the frame of a special wheeled chassis when it moves on roads of various categories. Based on the developed finite element model of the frame, we obtained and analyzed full-size patterns of the stress-strain state of the frame and oscillograms of equivalent stresses in the most loaded zones of the frame.

scholarly journals Mathematical modeling of transformable space structure dynamics

2019 ◽  
Vol 221 ◽  
pp. 01018 ◽  
Author(s):  
Vladimir Zimin ◽  
Alexey Krylov ◽  
Sergey Churilin ◽  
Zikun Zhang
Keyword(s):  
Strain State ◽  
Element Model ◽  
Space Structure ◽  
Space Structures ◽  
Elastic Rod ◽  
Stress Strain ◽  
Large Space ◽  
Structure Dynamics ◽  
Stress Strain State ◽  
Large Space Structure

Today large space structures are in focus of attention of engineers and designers of rocket and space equipment. In ground-based experiments, it is not always possible to carry out complex tests of large space structure functionality. Therefore, the development of mathematical models describing properly the transformable structure dynamics when they opened from the densely packed transport state to the operating position in the orbit becomes very important. To determine the stress-strain state of the frame elements when it is unfolding the shape of the framework is taken at the moments when relative velocities of the adjacent sections are maximal. Supposed, that at these moments the frame elements are getting on the stops limiting their relative angular displacements, and the structure behaves as an elastic rod with specified characteristics. Numerical analysis of the stress-strain state in the framework is carried out by means of a finite element model. Therefore, the represented mathematical model can be effectively used to predict the functional suitability of such transformable space structures already on the early stages of their development.

Quadrilateral Shape Rib Forming by Roll Forming Process

2018 ◽  
Vol 878 ◽  
pp. 296-301
Author(s):  
Dong Won Jung
Keyword(s):  
Automotive Industry ◽  
High Strength Steel ◽  
Numerical Study ◽  
Thickness Distribution ◽  
High Strength ◽  
Metal Sheet ◽  
Product Performance ◽  
Roll Forming ◽  
Forming Process ◽  
Roll Forming Process

The roll forming is one of the simplest manufacturing processes for meeting the continued needs of various industries. The roll forming is increasingly used in the automotive industry to form High Strength Steel (HSS) and Advanced High Strength Steel (AHSS) for making structural components. In order to reduce the thinning of the sheet product, traditionally the roll forming has been suggested instead of the stamping process. The increased product performance, higher quality, and the lowest cost with other advantages have made roll forming processes suitable to form any shapes in the sheets. In this numerical study, a Finite Element Method is applied to estimate the stress, strain and the thickness distribution in the metal sheet with quadrilateral shape, ribs formed by the 11 steps roll forming processes using a validated model. The metal sheet of size 1,000 × 662 × 1.6 mm taken from SGHS steel was used to form the quadrilateral shape ribs on it by the roll forming process. The simulation results of the 11 step roll forming show that the stress distribution was almost uniform and the strain distribution was concentrated on the ribs. The maximum thinning strain was observed in the order of 15.5 % in the middle rib region possibly due to the least degree of freedom of the material.

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