Abstract
Abstract. Laser metal deposition (LMD) is a laser-based additive manufacturing (AM) technology that offers significant advantages in the production and repair of bespoke and valuable parts targeting applications in the aerospace, tooling and medical industries. A significant problem with AM is the development of high residual stresses, deformation and cracking. Advanced sensing technologies can be a useful tool for characterising residual stress (RS) and the structural response of AM aerospace components under fatigue loading conditions. This paper reports on a feasibility study assessing the performance of fibre optic (FO) distributed strain measurement technology to measure surface RS in comparison to traditional electrical resistance strain gauges and the contour method. The results from this study will be used to justify further experimental work.
Highlights
Laser metal deposition (LMD) applications have been targeted for repairing intricate geometries and structural restoration of specialised high value components such as sintered tools and aerospace components [1,2]
The highest residual stress (RS) was recorded in fibre optic (FO) L2, with a peak value of 153 MPa, while the peak stress value at maximum applied load occurred in FO L1
These results show that FO sensing (FOS) can provide a reasonable estimate for the RS distribution and of the peak stress at high load, for this application
Summary
LMD applications have been targeted for repairing intricate geometries and structural restoration of specialised high value components such as sintered tools and aerospace components [1,2]. Metallic powder is blown through a deposition nozzle and heated with a laser to produce a metallic bead that is deposited, layer by layer and track by track, to build-up a part or to add layers of material to an existing part. The nozzle system shrouds the work area with shield gas thereby eliminating the requirement for enclosures with controlled environments and providing exciting opportunities for Defence applications. LMD delivers high density deposited material with a strong metallurgical bond to the substrate. Similar to the HAZ in welding, RSs are detrimental to the structural integrity of the part, with warping and stress concentrations promoting fatigue cracking and inducing unpredictable buckling in service
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