On thermo-elastic-plastic analysis of heat-treatment processes including creep and phase changes

Rammerstorfer, F.G.; Fischer, Dieter F.; Mitter, Werner; Bathe, Klaus‐Jürgen; Snyder, Mark D.

doi:10.1016/0045-7949(81)90040-7

Cited by 74 publications

(25 citation statements)

References 9 publications

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“…Using a laser beam as a heat source forces alloys to yield plastically and/or causes an allotropic phase transformation then residual stresses remain in the heat affected zone after cooling down [5]. This well known fact is the initial approach to use residual stresses to affect the characteristics of thin walled metal sheets.…”

Section: Methodsmentioning

confidence: 99%

Improvement of buckling resistance of thin sheets by local laser treatment

Figala

Buchmayr

2010

Int J Mater Form

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Lightweight thin walled structures are primarily dimensioned for stiffness of the whole construction and less for material resistance. Usual design concepts for improving the stability behaviour of metal sheets introduce the configuration of fins, stiffeners, beads or embossing patterns. However these methods not only increase the moment of inertia but also the weight of the component. In this paper an alternative method for inserting residual stresses is presented and the influence of the static and dynamic behaviour is shown. Local laser spots and laser lines are introduced in order to achieve proper distributions of residual stresses. The effect on fundamental frequency and buckling resistance was investigated on steel sheets of 280 mm x 280 mm and a thickness of 0.75 mm in a special testing rig. Buckling load and mid-point displacement were measured by a LVDT-system. Correlations between residual stresses, fundamental frequency and buckling resistance could be found. During buckling tests the uniaxial applied load vs. mid-point deflection was measured. In order to illustrate the improvements of the buckling load, fundamental frequency and residual stresses have been analysed. In conclusion, the laser treatment and the insert of residual stress patterns by laser treatment, respectively, is a promising method to increase the static and dynamic behaviour for thin walled metal sheets.

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Section: Methodsmentioning

confidence: 99%

Improvement of buckling resistance of thin sheets by local laser treatment

Figala

Buchmayr

2010

Int J Mater Form

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“…For nonlinear problems, it is imperative to iterate for tight tolerance within each time step of the calculation, e.g. see Rammerstorfer et al (1981) and Bathe and Khoshgoftaar (1979). The total damping matrix C t of the total coupled problem (68) can be written as…”

Section: The Solution Proceduresmentioning

confidence: 99%

Development of a Generalized Version of the Poisson– Nernst–Planck Equations Using the Hybrid Mixture Theory: Presentation of 2D Numerical Examples

Johannesson

2010

Transp Porous Med

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A numerical scheme for the transient solution of a generalized version of the Poisson-Nernst-Planck (PNP) equations is presented. The finite element method is used to establish the coupled non-linear matrix system of equations capable of solving the present problem iteratively. The PNP equations represent a set of diffusion equations for charged species, i.e. dissolved ions, present in the pore solution of a rigid porous material in which the surface charge can be assumed neglectable. These equations are coupled to the 'internally' induced electrical field and to the velocity field of the fluid. The Nernst-Planck equations describing the diffusion of the ionic species and Gauss' law in use are, however, coupled in both directions. The governing set of equations is derived from a simplified version of the so-called hybrid mixture theory (HMT). The simplifications used here mainly concerns ignoring the deformation and stresses in the porous material in which the ionic diffusion occurs. The HMT is a special version of the more 'classical' continuum mixture theories in the sense that it works with averaged equations at macroscale and that it includes the volume fractions of phases in its structure. The background to the PNP equations can by the HMT approach be described by using the postulates of mass conservation of constituents together with Gauss' law used together with consistent constitutive laws. The HMT theory includes the constituent forms of the quasistatic version of Maxwell's equations making it suitable for analyses of the kind addressed in this work. Within the framework of HTM, constitutive equations have been derived using the postulate of entropy inequality together with the technique of identifying properties by Lagrange multipliers. These results will be used in obtaining a closed set of equations for the present problem.

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“…It is important to consider that during solid phase transformations the yield stress has to be determined using, in a weighted average, the yield stress of each phase and also taking into account the phenomenon of transformation plasticity which is discussed in References [22] and [23].…”

Section: Inclusion Of Thermal Strains In the Flow Formulationmentioning

confidence: 99%

A new rigid‐viscoplastic model for simulating thermal strain effects in metal‐forming processes

Dvorkin¹,

Toscano²

2003

Numerical Meth Engineering

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SUMMARYA new rigid-viscoplastic model that includes the e ect of thermal strains when modelling steady-state metal-forming processes was developed. A symmetric approximation to the resulting non-symmetric stiness matrix was derived. The thermo-mechanical ow formulation was implemented using the pseudoconcentrations technique. The new formulation was numerically tested showing that it provides reliable results.

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On thermo-elastic-plastic analysis of heat-treatment processes including creep and phase changes

Cited by 74 publications

References 9 publications

Improvement of buckling resistance of thin sheets by local laser treatment

Improvement of buckling resistance of thin sheets by local laser treatment

Development of a Generalized Version of the Poisson– Nernst–Planck Equations Using the Hybrid Mixture Theory: Presentation of 2D Numerical Examples

A new rigid‐viscoplastic model for simulating thermal strain effects in metal‐forming processes

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