Design of Forging Process Parameters With Deformation and Temperature Constraints

1996 ◽  
Vol 118 (3) ◽  
pp. 441-444 ◽  
Author(s):  
R. V. Grandhi ◽  
H. Cheng ◽  
S. S. Kumar
Keyword(s):  
Process Parameters ◽  
Thermal Analyses ◽  
Linear Quadratic Regulator ◽  
Work Piece ◽  
Fe Model ◽  
Linear Quadratic ◽  
Fe Method ◽  
Time Control ◽  
State Space System ◽  
Nonlinear Rigid

This paper presents a methodology for designing optimal process parameters for forging operations. The nonlinear rigid viscoplastic finite element (FE) method is used for deformation and thermal analyses. From the FE model a state space system is developed for representing the coupled deformation and thermal behavior of the metal forming system. Constraints are imposed on the strain rate and temperature of the deforming work-piece for obtaining the desired physical/microstructural properties in the final product. The linear quadratic regulator (LQR) theory for finite time control is used in designing the initial die temperature and optimal ram velocity schedules. The approach is demonstrated on a plane strain channel section forging under nonisothermal conditions.

Optimal Design of Forging Processes With Deformation and Temperature Constraints

1993 ◽  
Author(s):  
R. V. Grandhi ◽  
H. Cheng ◽  
S. S. Kumar
Keyword(s):  
Thermal Analyses ◽  
State Space Model ◽  
Linear Quadratic Regulator ◽  
Parameter Design ◽  
Linear Quadratic ◽  
Optimal Control Strategy ◽  
Time Control ◽  
Systematic Methodology ◽  
Element Approach ◽  
Nonisothermal Conditions

Abstract This paper presents a systematic methodology for the design of process parameters for nonisothermal forgings. The finite element approach is used for deformation and thermal analyses, and an optimal control strategy is used for the process parameter design. A state-space model is developed for representing the coupled deformation and thermal behavior using rigid viscoplastic formulation. Design constraints on strain-rates and temperature variation are imposed for achieving the desired forging conditions. The linear quadratic regulator (LQR) theory for finite time control is used in designing the ram velocity and initial die temperature. The approach is demonstrated on an axisymmetric disc forging and a plane strain channel section forging, under nonisothermal conditions.

Optimized Near Minimum Time Control of Flexible Structures Using Variable Gain (LQG) Control Strategies

2005 ◽  
Vol 128 (3) ◽  
pp. 402-407 ◽  
Author(s):  
Rajiv Kumar ◽  
S. P. Singh ◽  
H. N. Chandrawat
Keyword(s):  
Control Strategies ◽  
Flexible Structures ◽  
Linear Quadratic Regulator ◽  
Control Voltage ◽  
Control Input ◽  
Linear Quadratic ◽  
Variable Gain ◽  
Time Control ◽  
Present Technique ◽  
Time Optimal

A neural network based time optimal control of flexible structures is presented. The implementation is done on a flexible inverted L structure with surface-bonded piezoceramic sensors/actuators. The state-space presentation, from control input voltages to sensor output voltages is established in multivariable form. A variable gain multi-input multi-output linear quadratic regulator controller is designed and implemented. The controller gains are varied as the modal energy of the system decreases. The gains are varied in such a manner that the system utilizes maximum control energy from fixed amplitude of control voltage. The gains are calculated by solving the Riccatti equation with weightage in performance index that varies according to the states of the system. Thus at periodic intervals, the gains are updated to fully utilize the available control voltage. Comparison of the present technique is done with the classical bang-bang controller.

Simulation of Residual Stress in Ultrasonic Vibration Assisted Micro-Milling

2011 ◽  
Vol 188 ◽  
pp. 381-384 ◽  
Author(s):  
Hai Jun Hu ◽  
Ya Zhou Sun ◽  
Z.S. Lu
Keyword(s):  
Residual Stresses ◽  
Ultrasonic Vibration ◽  
Process Parameters ◽  
Shear Failure ◽  
Sliding Friction ◽  
Micro Milling ◽  
Work Piece ◽  
Fe Model ◽  
Optimal Process ◽  
Surface Residual Stresses

The machining-induced residual stresses are strongly dependent on the work-piece material and the chosen process parameters. A 2D finite element (FE) model of ultrasonic vibration assisted micro-milling (UVAMM) is established using ABAQUS. Johnson-Cook’s work-piece material and shear failure principle are used, while friction between tool and work-piece uses modified Coulomb’s law whose sliding friction area is combined with sticking friction. By means of FE analysis, the influence rules of spindle speed, vibration frequency and work-piece material on the surface residual stresses are obtained, which provides a basis for choosing optimal process parameters and improving the longevity and reliability of micro-component.

A Study on Linear Quadratic Regulator with the Desired Low-Pass Property

2013 ◽  
Vol 133 (12) ◽  
pp. 2167-2175 ◽  
Author(s):  
Katsuhiko Fuwa ◽  
Satoshi Murayama ◽  
Tatsuo Narikiyo
Keyword(s):  
Linear Quadratic Regulator ◽  
Linear Quadratic ◽  
Low Pass

A novel model of Z-pin insertion in prepreg based on fracture mechanics

2021 ◽  
pp. 095440542110144
Author(s):  
Guobiao Ji ◽  
Liang Cheng ◽  
Shaohua Fei ◽  
Jiangxiong Li ◽  
Yinglin Ke
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Analytical Model ◽  
Model Parameters ◽  
Force Model ◽  
Fe Model ◽  
Cohesive Elements ◽  
Fe Method ◽  
Insertion Force ◽  
Mechanics Model

Through-thickness reinforcement is a promising solution to the problem of delamination susceptibility in laminated composites. Modeling Z-pin–prepreg interaction is essential for accurate robotics-assisted Z-pin insertion. In this paper, a novel Z-pin insertion force model combining the classical cohesive finite element (FE) method with a dynamic analytical fracture mechanics model is proposed. The velocity-dependent cohesive elements, in which the fracture toughness is provided by the analytical model, are implemented in Z-pin insertion FE model to predict the crack initiation and propagation. Then Z-pin insertion experiments are performed on prepreg sample with metallic Z-pins at different velocities to identify the analytical model parameters and validate the simulation predictions offered by the model. Dynamics of Z-pin interaction with inhomogeneous prepreg is described and the effects of insertion velocity on prepreg contact force are studied. Results show that the force model agrees well with experiments and the fracture toughness rises with the increasing Z-pin insertion velocity.

Development and analysis of composite overwrapped pressure vessels for hydrogen storage

2021 ◽  
pp. 002199832110335
Author(s):  
Osman Kartav ◽  
Serkan Kangal ◽  
Kutay Yücetürk ◽  
Metin Tanoğlu ◽  
Engin Aktaş ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Damage Model ◽  
Pressure Vessels ◽  
Filament Winding ◽  
Burst Pressure ◽  
Fe Model ◽  
Fe Method ◽  
Liner Material ◽  
Mechanical Performances ◽  
Metallic Liner

In this study, composite overwrapped pressure vessels (COPVs) for high-pressure hydrogen storage were designed, modeled by finite element (FE) method, manufactured by filament winding technique and tested for burst pressure. Aluminum 6061-T6 was selected as a metallic liner material. Epoxy impregnated carbon filaments were overwrapped over the liner with a winding angle of ±14° to obtain fully overwrapped composite reinforced vessels with non-identical front and back dome layers. The COPVs were loaded with increasing internal pressure up to the burst pressure level. During loading, deformation of the vessels was measured locally with strain gauges. The mechanical performances of COPVs designed with various number of helical, hoop and doily layers were investigated by both experimental and numerical methods. In numerical method, FE analysis containing a simple progressive damage model available in ANSYS software package for the composite section was performed. The results revealed that the FE model provides a good correlation as compared to experimental strain results for the developed COPVs. The burst pressure test results showed that integration of doily layers to the filament winding process resulted with an improvement of the COPVs performance.

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