Second Generation weld heat source models replace the point, line and plane models that mathematically are delta functions, with distribution functions. The first of these was a distributed flux model by Pavelic [19] and by Rykalin [17], see Chapter II. This distributed flux model was particularly effective for low power density welds in which the […]

First Generation weld heat source models are the point, line and plane heat source models of Rosenthal [18] and Rykalin [17]. They are the first and most famous of weld heat source models. The point source specifies the position of the weld and the net total rate of heat input from the weld source (J/s). […]

Having specified the data available to characterize the weld heat source, the next step is to decide how to use the available data to compute the transient temperature field of the weld in the structure being welded. The most popular approaches are listed below. They are roughly in chronological order because the more recent generations […]

The best way of modeling a weld heat source depends on many factors. The first factor to consider is how accurately we want to model the heat source. Few if any welding processes used in industry are controlled more accurately than 5% and many are controlled less accurately. Our knowledge of the values of material […]

What we know about a weld heat source either comes from experimental observation or more detailed models of the welding process. Experimentally, currents, voltages, frequency, wire feed rates, welding speeds, etc. can be measured. Also welds can be sectioned and cross-sections of a weld measured optically. Various forms of video cameras, some with laser illumination, […]

For the moment we will assume that the velocity of the material points is zero. However, the arc is allowed to move with some velocity. Also an observer is allowed to move with some velocity. We will state the mathematics more precisely later but here we simply want to present an intuitive view of terms […]

3.1 Introduction and Synopsis The conservation of energy is the fundamental principle in thermal analysis. Therefore in heat transfer theory, we are concerned with energy and ignore stress, strain and displacement. The principal phenomena are shown in Figure 3-1. Figure 3-1: The important phenomena that should be captured in models for heat transfer analysis are […]

Since the Finite Element Method (FEM) is primarily an exercise in numerical integration, it is not surprising that better integration schemes are being sought. Numerical integration schemes replace an integral by a summation; e. g. J f(x)dx — ]T"=1 wif(xi). The choice of the number of sampling points, i, the weights, wt, and the location […]

Many failures of welds initiate in the heat affected zone adjacent to the weld metal, e. g., in the coarse grained HAZ. For this reason, welding engineers devote much of their effort to controlling the microstructure and hence toughness of the HAZ. Metallurgists usually describe the evolution of microstructure in low alloy steels with isothermal […]

The thermal stress analysis of welds is more complex than the heat flow analysis because of the geometry changes and because of the complex stress-strain relationship. In designing a welding procedure, the critical issues are defects, mechanical properties, distortion and residual stress. Modeling stresses in welds includes all distortions that can be predicted by thermal […]