TAILIEUCHUNG - Study of prestrain influence for the prediction of the necking occurrence

This paper contains experimental results for mechanical characteristics of a mild steel sheet. The determination of the forming limit stress curve for solicitation along two direction is drawn. Study of prestrain influence from the limit stress diagram is presented. | Vietnam Journal of Mechanics, NCST of Vietnam Vol. 21 1 1999, No 1 {57- 64} STUDY OF PRESTRAIN INFLUENCE FOR THE PREDICTION OF THE NECKING OCCURRENCE NGUYEN NHAT THANG Hanoi University of Technology ABSTRACT. This paper contains experimental results for mechanical characteristics of a mild steel sheet. The determination of the forming limit stress curve for solicitation along two direction is drawn. Study of prestrain influence from the limit stress diagram is presented. - §1. Introduction The industrial blank usually show complex strain-paths, so the use of forming limits diagram, draw for rectilinear strain-paths can not allow to predict the success of a drawing operation in press shop. In some works we have seen the existence of a single forming limits stress curve which is independent on the strain path shape, while the classical forming limit curves are dependent on them !or an orthotropic sheet-steel (2], (3], (6]. In previous work [11], we have shown the strain path influence on the forming limit diagram. Here, we determine the stress states at the onset of necking for rolling and transverse directions of sheet-steel. Then we present the forming limit diagrams calculated for different prestrains. §2. Determination of the forming limits stress curves for solicitation along rolling and transverse directions The experimental results have been obtained from a mild steel sheet named SE DDR-T700 of thickness . - Elastic limits along the rolling and transverse directions O'Q = 166; u 90 = 170 (MPa) - Landkford's coefficients along two directions: ro = ; rgo = 57 Variation of two coefficients is presented on Fig. 1 r 2 0 0 r0 = 1,5 0,5 ·o ~----+-----~----~-----+----~~----~--- 5 1D f5 20 25 30 % f . Variation of anisotropic coeficient - Hill'~ coefficients [5] F = ; G = ; H = (MPa- 112 ). The forming limit diagrams are determined by means of a ¥arciniak's device. The strain at the onset of necking are

• Vật lý
• Vietnam Journal of Mechanics
• Study of prestrain influence for the prediction
• The necking occurrence
• The limit stress diagram
• The forming limit stress curve
• Dang Dinh Ang
• Nonlinear analysis and mechanics
• Dynamic problems involving stationary cracks
• The Wiener Hopt technique
• Dual integral equations
• Dual integrals in non linear fracture mechanics
• Non linear fracture mechanics
• Energy release rate
• Discuss the obtained
• The alpha finite element method (αFEM)
• Solid mechanics using triangular and tetrahedral elements
• Suitable computational cost
• NS FEM makes
• The upper bound property
• Non linear constitutive problems in solid mechanics
• Non linear constitutive problems
• Languages Gibian and special operators
• The application FEM
• Betts miller janjic convective parameterization scheme
• H14 31 model to forecast heavy rainfall in Vietnam
• Betts Miller Janjic
• Three rain seasons
• Manufacturing dry mixed cement mortar
• High compressive strength
• High flexural strength
• Low shrinkage and high watertightness for restoration
• Damaged hydraulic structures in Vietnam
• Standard gradient models and crack simulation
• Standard gradient models
• The propagation of cracks
• Damage mechanics and crack simulation
• The interaction between two parametric excitations
• The second and third degrees
• The asymptotic method of nonlinear mechanics
• Dynamic system governed
• Comparison of two hydrological model simulations
• Nam and Xinanjiang for Nong Son catchment
• The Central Vietnam
• The runoff components
• 3 D numerical simulation
• The tidal circulation
• The gulf of Tonkin
• The kinetic energy distribution
• Duality in the analysis of responses to nonlinear systems
• The analysis of responses
• The original nonlinear systems
• The study of nonlinear mechanics
• Aerodynamics of a wing in surface effect ship
• Theory and experiment
• Wing in surface effect ship
• The aerodynamic characteristics
• The Institute of Mechanics
• The error estimate
• The convergence rate for h
• p refinement
• The finite element analysis
• Three dimensional elastostatic mechanics problems
• Some initial experimental results
• Free water layer formation in horizontal pipes
• Water layer formation
• Hanoi Institute of Mechanics
• Bending vibration of beam elements under moving loads
• Considering vehicle braking forces
• Fluctuations of structures
• Beam elements according
• Continuous element for vibration analysis
• Thick shells of revolution
• Continous Element Method
• Finite element solutions
• Natural frequencies and harmonic responses
• Cast3m implementation of the extended finite element method
• The extended finite element method for cohesive crack
• Quasi brittle materia
• The proposed implementation
• The displacement discontinuities
• Buckling analysis of simply supported composite laminates subjected
• In plane compression load
• A novel mesh ffree method
• Alternative numerical technique
• Mesh free method
• A three story building
• Hedge algebras based fuzzy controller
• The structural system
• The El Centro earthquake
• Three story building against earthquake
• Laminar separation phenomenon combining with numerical calculations
• The turbulent separation
• The laminar separation
• Experimental study on mechanical properties
• Three phase polymer composite reinforced
• Glass fibers and titanium oxide particles
• Polymer composite reinforced
• Three phase composite
• Dynamic characteristics of elastically supported beam subjected
• A compressive axial force and a moving load
• The implicit Newmark method
• The Galerkin finite element method
• The axial force
• Eccentrically stiffened functionally graded plates and shallow shells
• Von Karman Donnell sense
• The formulation of governing equations
• The classical shell theory
• Mathematical modelling and control of the evolution
• Dynamic systems interacting with medium
• Mathematical modeling evolutional systems interacting
• Two conjugate mechanical subsystems
• Evaluating structural safety based on fuzzy set theory
• Evaluating structural safety
• The fuzzy reliability
• Simple beam structure