Abstract
This paper presents a finite element thermal model for linear friction welding applied to an instrumented weld in Ti6Al4V. The power at the weld interface was estimated from the measured transverse velocity and the cyclic machine load. This was compared with the power history reverse-engineered from thermocouple data. A simple analytical model captured the lateral distribution of heat input at the interface, while geometry changes and heat loss due to the expulsion of flash were included using a sequential step-wise technique, removing interface elements one layer at a time at discrete intervals. Comparison of predicted and experimental power showed a 20% discrepancy, attributed to uncertainty in the power estimate from force and displacement data, and sensitivity to the precision of locating the thermocouples. The thermal model is computationally efficient, and is sufficiently accurate for application to a new thermomechanical modelling approach, developed in a subsequent paper [1].
Highlights
Linear friction welding (Fig. 1) is a solid state joining method, in which a component subjected to reciprocating transverse motion is pressed against a stationary component
This paper presents the first part of this new approach – an implicit FE thermal model of LFW, to predict the temperature field for the entire weld duration
One challenging aspect of modelling LFW with the proposed small-strain framework is the need to handle the change of geometry associated with burn-off. This is achieved in the thermal model by “deleting” layers of elements at the interface at intervals, with each layer of elements corresponding to an equivalent volume of material extruded to flash
Summary
Linear friction welding (Fig. 1) is a solid state joining method, in which a component subjected to reciprocating transverse motion is pressed against a stationary component. The growth of intermetallic compounds can be controlled when welding dissimilar metals. It is fast and repeatable, easy to automate, energy efficient, and requires little preparation of joined surfaces with no shielding gas or consumables [3, 4]. Titanium is well-suited for LFW because of its mechanical properties and low thermal conductivity, which confines heat to the welded interface. The impact of the α-β transition on the deformation in linear friction welds of Ti is discussed in the subsequent paper on modelling of the heat generation [1]
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