scholarly journals Plastic forming processes of transverse non-homogeneous composite metallic sheets

2021 ◽  
Vol 11 (1) ◽  
pp. 294-302
Author(s):  
Gal Davidi
Keyword(s):  
Inner Core ◽  
Plastic Material ◽  
Radial Solution ◽  
Algebraic Differential Equation ◽  
Forming Process ◽  
Perfectly Plastic ◽  
Plastic Forming ◽  
Validity Limit ◽  
Significant Achievement

Abstract In this work an analysis of the radial stress and velocity fields is performed according to the J 2 flow theory for a rigid/perfectly plastic material. The flow field is used to simulate the forming processes of sheets. The significant achievement of this paper is the generalization of the work by Nadai & Hill for homogenous material in the sense of its yield stress, to a material with general transverse non-homogeneity. In Addition, a special un-coupled form of the system of equations is obtained where the task of solving it reduces to the solution of a single non-linear algebraic differential equation for the shear stress. A semi-analytical solution is attained solving numerically this equation and the rest of the stresses term together with the velocity field is calculated analytically. As a case study a tri-layered symmetrical sheet is chosen for two configurations: soft inner core and hard coating, hard inner core and soft coating. The main practical outcome of this work is the derivation of the validity limit for radial solution by mapping the “state space” that encompasses all possible configurations of the forming process. This configuration mapping defines the “safe” range of configurations parameters in which flawless processes can be achieved. Several aspects are researched: the ratio of material's properties of two adjacent layers, the location of layers interface and friction coefficient with the walls of the dies.

Case Study of Shakedown Evaluation of a Shell With Nozzle Based on Elastic-Plastic Analysis

2017 ◽  
Author(s):  
Jun Shen ◽  
Heng Peng ◽  
Liping Wan ◽  
Yanfang Tang ◽  
Yinghua Liu
Keyword(s):  
Temperature Change ◽  
Plastic Material ◽  
Material Model ◽  
Elastic Plastic ◽  
Perfectly Plastic ◽  
Plastic Analysis ◽  
Elastic Perfectly Plastic ◽  
Temperature Loads ◽  
The Impact

In the past, shakedown evaluation was usually based on the elastic method that the sum of the primary and secondary stress should be limited to 3Sm or the simplified elastic-plastic analysis method. The elastic method is just an approximate analysis, and the rigorous evaluation of shakedown normally requires an elastic-plastic analysis. In this paper, using an elastic perfectly plastic material model, the shakedown analysis was performed by a series of elastic-plastic analyses. Taking a shell with a nozzle subjected to parameterized temperature loads as an example, the impact of temperature change on the shakedown load was discussed and the shakedown loads of this structure at different temperature change rates were also obtained. This study can provide helpful references for engineering design.

scholarly journals A Simplified Approach for the Hydro-Forming Process of Bi-Metallic Composite Pipe

2017 ◽  
Vol 62 (2) ◽  
pp. 879-883 ◽  
Author(s):  
M. Zheng ◽  
H. Gao ◽  
H. Teng ◽  
J. Hu ◽  
Z. Tian ◽  
...  
Keyword(s):  
Residual Stress ◽  
Plastic Material ◽  
Material Model ◽  
Forming Process ◽  
Simplified Approach ◽  
Metallic Composite ◽  
Perfectly Plastic ◽  
Proposed Model ◽  
Composite Pipe ◽  
Elastic Perfectly Plastic

AbstractIn this article, it aims to propose effective approaches for hydro-forming process of bi-metallic composite pipe by assuming plane strain and elastic-perfectly plastic material model. It derives expressions for predicting hydro-forming pressure and residual stress of the forming process of bi-metallic composite pipe. Test data from available experiments is employed to check the model and formulas. It shows the reliability of the proposed model and formulas impersonally.

scholarly journals RANCANG BANGUN MOLD UNTUK PROSES TERMOFORMING PROSTHETIC BELOW KNEE (B/K)

2017 ◽  
Vol 18 (2) ◽  
Author(s):  
Bambang Waluyo Febriantoko ◽  
Aris Aryanto ◽  
Tri Widodo Besar Riyadi
Keyword(s):  
Plastic Material ◽  
Forming Process ◽  
Temperature Variations ◽  
Plastic Shrinkage ◽  
Pressing Process ◽  
Plastic Forming ◽  
Thermoforming Process ◽  
Good Expansion

ABSTRAK Industri semakin berkembang, kebutuhan terhadap plastik pun semakin bertambah. Akan tetapi, dalam aplikasi proses pembentukan plastik sering mengalami kendala. Salah satunya adalah penyusutan. Penyusutan sering terjadi pada proses pembentukan plastik, terutama pembentukan dengan sistem mechanical thermoforming. Sehingga perlu dianalisis hal-hal yang menyebabkan penyusutan pada produk yang dihasilkan. Beberapa hal yang diidentifikasi mempengaruhi terjadinya penyusutan adalah bentuk mold, temperatur, dan jenis plastik yang digunakan.Metode penelitian yang digunakan adalah membuat alat uji mechanical thermoforming dan  membuat  mold  yang  akan  digunakan  untuk  menganalisis  penyusutan.  Mold yang digunakan ada 2 macam, yaitu mold telapak kaki atas dan mold telapak kaki bawah. Selain variasi pada mold, analisis juga ditujukan pada temperatur plastik polypropylene (PP) dan plastik PVC yang akan diproses. Variasi temperatur yaitu:1000C,  1200C,  dan  140oC.  Sedangkan  jenis  plastik  yang  diujikan  adalah  plastikpolypropylene (PP) dan plastik PVC.Dari data hasil pengujian dan pembahasan pada proses mechanical thermoforming untuk plastik polypropylene (PP) dengan ketebalan 1,0 mm tidak dapat dianalisis persentase penyusutan yang terjadi karena sifat viskos pada plastik rendah. Pada plastik jenis PP ini meskipun membentuk pola, tetapi tidak sempurna. Bahan plastik PP setelah proses penekanan dengan temperatur 100ºC-120ºC plastik tidak mengalami pemuaian yang cukup baik, karena plastik masih bersifat elastik. Pada temperatur140ºC plastik mengalami pemuaian, tetapi saat proses penekanan plastik mengalami bentuk pola yang tidak sempurna, karena temperatur terlalu tinggi. Sedangkan pada plastik PVC didapatkan hasil bahwa pada mold telapak kaki atas dengan ketinggian2 cm dan tebal plastik 1,0 mm menghasilkan persentase penyusutan rata-rata 7,85% dengan temperatur 100ºC, 9,80% dengan temperatur 120ºC dan 12,11% dengan temperatur 140ºC. Pada mold telapak kaki bawah dengan ketinggian 2 cm dan tebal plastik 1,0 mm menghasilkan persentase penyusutan rata-rata 10,01% dengan temperatur 100ºC, 10,96% dengan temperatur 120ºC dan 12,08% dengan temperatur140ºC. Kata Kunci: Mechanical thermoforming, penyusutan plastik, mold ABSTRACT The growing of industry has the effect to the increase of plastic need.  However, the application of plastic forming process often experiences constraints. One of them is depreciation. Depreciation often occurs in the plastic forming process, especially forming with mechanical thermoforming system. So it is necessary to analyze the things that cause shrinkage on the product. Some of the things that are identified to influence the shrinkage are the molds, temperatures and types of used plastics.The used method is to make mechanical thermoforming test and make mold which will be used to analyze depreciation. There are 2 kinds of molds, namely upper foot sole mold and bottom foot sole mold. In addition to the variations of the mold, the analysis is also aimed at the temperature of polypropylene plastic (PP) and PVC plastic which will be processed. The temperature variations are 1000C, 1200C and 140oC and the types of plastics that are tested is polypropylene plastic (PP) and PVC plastic.The results show that on mechanical thermoforming process for polypropylene (PP) plastic with 1.0 mm thickness, the percentage of shrinkage can not be analyzed because of the low viscous nature of plastic. PP type plastic can form a pattern, but not perfect. PP plastic material does not experience a good expansion after pressing process with100ºC-120ºC plastic temperature. This is because the plastic is still elastic. At 140ºC, the plastic undergoes expansion, but when the plastic pressing process, it undergoes an imperfect pattern. The reason is the temperature is too high. Meanwhile for the PVC plastic, it was found that in the upper foot sole mold with height of 2 cm and 1.0 mm plastic thickness, the percentages of shrinkage average are 7.85% with temperature100ºC, 9.80% with temperature 120ºC and 12.11% with temperature of 140ºC. In the bottom foot sole mold with 2 cm height and 1.0 mm plastic thickness, the percentages of shrinkage average are 10.01% with temperature 100ºC, 10.96% with temperature120ºC and 12.08% with temperature 140ºC. Keywords: Mechanical thermoforming, plastic shrinkage, mold

Spatial free plastic forming of slender parts—numerical approaches for strain-hardening material

2004 ◽  
Vol 218 (6) ◽  
pp. 641-650 ◽  
Author(s):  
M Thalmair ◽  
H Lippmann
Keyword(s):  
Strain Hardening ◽  
Metal Forming ◽  
Plastic Material ◽  
Forming Process ◽  
Hardening Material ◽  
Final Shape ◽  
Metal Forming Process ◽  
Plastic Forming ◽  
Elastic Plastic Material ◽  
Numerical Approaches

A new metal forming process is described in which a slender part may be brought to a prescribed final shape by means of an appropriate, pre-calculated motion of its free ends only. Corresponding calculation schemes are presented for elastic/plastic material with strain hardening, and these are illustrated by practical examples.

Construction of plastic contact deformation maps on ceramics: a case study on aluminum nitride

1996 ◽  
Vol 54 ◽  
pp. 636-637
Author(s):  
D. L. Callahan
Keyword(s):  
Plastic Deformation ◽  
Aluminum Nitride ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Bright Field Image ◽  
Perfectly Plastic ◽  
Contrast Analysis ◽  
Deformation Patterns

Modern polishing, precision machining and microindentation techniques allow the processing and mechanical characterization of ceramics at nanometric scales and within entirely plastic deformation regimes. The mechanical response of most ceramics to such highly constrained contact is not predictable from macroscopic properties and the microstructural deformation patterns have proven difficult to characterize by the application of any individual technique. In this study, TEM techniques of contrast analysis and CBED are combined with stereographic analysis to construct a three-dimensional microstructure deformation map of the surface of a perfectly plastic microindentation on macroscopically brittle aluminum nitride.The bright field image in Figure 1 shows a lg Vickers microindentation contained within a single AlN grain far from any boundaries. High densities of dislocations are evident, particularly near facet edges but are not individually resolvable. The prominent bend contours also indicate the severity of plastic deformation. Figure 2 is a selected area diffraction pattern covering the entire indentation area.

A Study on the Flow Behavior of 42CrMo Steel under Hot Compression by Thermal Physical Simulations

2010 ◽  
Vol 108-111 ◽  
pp. 494-499
Author(s):  
Ying Tong ◽  
Guo Zheng Quan ◽  
Gang Luo ◽  
Jie Zhou
Keyword(s):  
Strain Rate ◽  
Flow Behavior ◽  
Rate Sensitivity ◽  
Strain Hardening Exponent ◽  
Forming Process ◽  
Material Parameters ◽  
Basic Model ◽  
42Crmo Steel ◽  
Plastic Forming ◽  
Physical Simulations

This work was focused on the compressive deformation behavior of 42CrMo steel at temperatures from 1123K to 1348K and strain rates from 0.01s-1 to 10s-1 on a Gleeble-1500 thermo-simulation machine. The true stress-strain curves tested exhibit peak stresses at small strains, after them the flow stresses decrease monotonically until high strains, showing a dynamic flow softening. And the stress level decreases with increasing deformation temperature and decreasing strain rate. The values of strain hardening exponent n, and the strain rate sensitivity exponent m were calculated the method of multiple linear regression, the results show that the two material parameters are not constants, but changes with temperature and strain rate. Then the two variable material parameters were introduced into Fields-Backofen equation amended. Thus the constitutive mechanical discription of 42CrMo steel which can accurately describe the relationships among flow stress, temperature, strain rate, strain offers the basic model for plastic forming process simulation.

The Kinematics Analysis and Study on Triangular Elbow Servo Press

2011 ◽  
Vol 121-126 ◽  
pp. 1636-1640
Author(s):  
Ying Qiu ◽  
Wei Min Li ◽  
Zhi Wei
Keyword(s):  
Optimization Design ◽  
Research Field ◽  
Transmission Mechanism ◽  
Kinematics Analysis ◽  
Servo Motor ◽  
Forming Process ◽  
Servo Press ◽  
Heavy Haul ◽  
Slider Motion

Servo presses are widely used in high-precision, complicated forming process fields and promoted around the world in recent years. It is the trend of forging machinery for its servo motor-based digital heavy haul driven technology. At present, it becomes the hot research field. The structure characteristics of triangular elbow servo press were firstly introduced in the paper. And then the kinematics mathematical model of triangular elbow transmission mechanism was deduced and given. Based on it, this paper provides the slider kinematics analysis by Matlab. The slider motion law under various parameters can be analyzed and compared. The results would be useful reference for optimization design of transmission mechanism. The case study provides more visual and reliable decision basis for designer.

Milling Curves Influence in Ring Rolling Processes

2014 ◽  
Vol 622-623 ◽  
pp. 956-963 ◽  
Author(s):  
Luca Giorleo ◽  
Elisabetta Ceretti ◽  
Claudio Giardini
Keyword(s):  
Numerical Approach ◽  
The Other ◽  
Ring Rolling ◽  
Roll Speed ◽  
Forming Process ◽  
Industrial Case Study ◽  
Industrial Environment ◽  
Ring Shape ◽  
Deformation Processes

Ring Rolling is a complex hot forming process used for the production of shaped rings, seamless and axis symmetrical workpieces. The main advantage of workpieces produced by ring rolling, compared to other technological processes, is given by the size and orientation of grains, especially on the worked surface which give to the final product excellent mechanical properties. In this process different rolls (Idle, Axial, Guide and Driver) are involved in generating the desired ring shape. Since each roll is characterized by a speed law that can be set independently by the speed law imposed to the other rolls, an optimization is more critical compared with other deformation processes. Usually, in industrial environment, a milling curve is introduced in order to correlate the Idle and Axial roll displacement, however it must be underlined that different milling curves lead to different loads and energy for ring realization. In this work an industrial case study was modeled by a numerical approach: different milling curves characterized by different Idle and Axial roll speed laws (linearly decreasing, constant, linearly increasing) were designed and simulated. The results were compared in order to identify the best milling curve that guarantees a good quality ring (higher diameter, lower fishtail) with lower loads and energy required for manufacturing.

Coupled Thermo-Mechanical FEA of Three-Roll Cross Rolling Process for Rings with Small-Hole and Deep Groove

2012 ◽  
Vol 560-561 ◽  
pp. 846-852 ◽  
Author(s):  
Qi Ma ◽  
Lin Hua ◽  
Dong Sheng Qian
Keyword(s):  
Rolling Process ◽  
Small Hole ◽  
Fe Model ◽  
Forming Process ◽  
Software Environment ◽  
Cross Rolling ◽  
Design And Optimization ◽  
Forming Technology ◽  
Deep Groove ◽  
Plastic Forming

Ring parts with small-hole and deep groove such as duplicate gear and double-side flange, are widely used in various engineering machineries. Three-roll cross rolling (TRCR) is a new advanced plastic forming technology for the processing of rings with small-hole and deep groove. In this paper, a 3D coupled thermo-mechanical FE model for TRCR of ring with small-hole and deep groove is established under ABAQUS software environment. By simulation and analysis, the evolution and distribution laws of strain and temperature in the forming process are revealed, and the effects of the key process parameters on the deformation uniformity are explored. The results provide valuable guideline for the technological parameter design and optimization.

On the Conditions to Prevent Plastic Shakedown of Structures: Part I—Theory

1993 ◽  
Vol 60 (1) ◽  
pp. 15-19 ◽  
Author(s):  
Castrenze Polizzotto
Keyword(s):  
Mechanical Load ◽  
Plastic Material ◽  
Perfectly Plastic ◽  
Shakedown Theory ◽  
Elastic Perfectly Plastic ◽  
Plastic Shakedown ◽  
Steady Load

For a structure of elastic perfectly plastic material subjected to a given cyclic (mechanical and/or kinematical) load and to a steady (mechanical) load, the conditions are established in which plastic shakedown cannot occur whatever the steady load, and thus the structure is safe against the alternating plasticity collapse. Static and kinematic theorems, analogous to those of classical shakedown theory, are presented.

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