COMPUTATIONAL WELDING MECHANICS

Starting Transient

When a real weld is started, the weld pool is not formed instantly. First, a Gaussian flux distribution heats the solid to the melting point, then a thin layer of molten metal forms. This grows in width and depth with time. With increasing depth, the weld pool surface is depressed and stirring is induced by electro-magnetic, buoyancy, arc pressure and surface tension gradient forces.

Modeling this starting transient is much more complex than modeling the steady-state weld pool. A simple technique is to hold the weld pool stationary for a few seconds. In practice, welders usually do this. The total energy input for the prescribed temperature heat source for time (0, t{) will equal the energy input for a constant power heat source for a time (0, t2), where (ti<t2). Using the shorter time, ti, with the prescribed temperature heat source reduces this error.

There is also a second order error in the starting transient temperature field because of time-dependent diffusion.

During the starting transient of the weld, the natural boundary condition models, i. e., thermal flux models develop the weld pool more realistically.

Current technology uses distribution functions with constant size and shape. It would be more realistic to interpolate the distribution function from a Gaussian flux distribution on starting to the steady state flux and power density distributions. The prescribed temperature distribution function is quite unrealistic on starting. In terms of an electrical circuit analogy, it applies a constant voltage for charging a capacitor. This results in a high power starting transient. However, the effect on the temperature field at later times is small and unless one is specifically interested in the starting transient, it can be neglected. It has been proposed that this problem could be resolved by applying the prescribed temperature heat source until the region near the weld pool reaches steady state. At that time compute the power density and flux distribution. Then restart the weld with this power density and flux distribution.

COMPUTATIONAL WELDING MECHANICS

Fracture Mechanics of Welded Structures

For fracture mechanics the location and geometry of the crack or defect must be specified as input data. The crack geometry could be specified as an ordered set of points …

Material Properties Summary

Properties can be provided for a material or alloy or for a specific phase in a material or alloy. If properties are provided for a specific phase, then the macroscopic …

Weld Pool Solver

If there is a weld pool solver that computes the weld pool free surface, velocity and temperature in the weld pool and weld pool reinforcement, the input data should include …

Как с нами связаться:

Украина:
г.Александрия
тел./факс +38 05235  77193 Бухгалтерия
+38 050 512 11 94 — гл. инженер-менеджер (продажи всего оборудования)

+38 050 457 13 30 — Рашид - продажи новинок
e-mail: msd@msd.com.ua
Схема проезда к производственному офису:
Схема проезда к МСД

Оперативная связь

Укажите свой телефон или адрес эл. почты — наш менеджер перезвонит Вам в удобное для Вас время.