TY  - JOUR
A1  - Fritsch, Tobias
A1  - Sprengel, Maximilian
A1  - Evans, Alexander
A1  - Farahbod-Sternahl, Lena
A1  - Saliwan-Neumann, Romeo
A1  - Hofmann, Michael
A1  - Bruno, Giovanni
T1  - On the determination of residual stresses in additively manufactured lattice structures
JF  - Journal of applied crystallography / International Union of Crystallography
N2  - The determination of residual stresses becomes more complicated with increasing complexity of the structures investigated. Additive manufacturing techniques generally allow the production of 'lattice structures' without any additional manufacturing step. These lattice structures consist of thin struts and are thus susceptible to internal stress-induced distortion and even cracks. In most cases, internal stresses remain locked in the structures as residual stress. The determination of the residual stress in lattice structures through nondestructive neutron diffraction is described in this work. It is shown how two difficulties can be overcome: (a) the correct alignment of the lattice structures within the neutron beam and (b) the correct determination of the residual stress field in a representative part of the structure. The magnitude and the direction of residual stress are discussed. The residual stress in the strut was found to be uniaxial and to follow the orientation of the strut, while the residual stress in the knots was more hydrostatic. Additionally, it is shown that strain measurements in at least seven independent directions are necessary for the estimation of the principal stress directions. The measurement directions should be chosen according to the sample geometry and an informed choice on the possible strain field. If the most prominent direction is not measured, the error in the calculated stress magnitude increases considerably.
KW  - additive manufacturing
KW  - laser powder bed fusion
KW  - residual stress
KW  - principal stress components
KW  - neutron diffraction
KW  - cellular structures
KW  - lattice structures
Y1  - 2021
U6  - https://doi.org/10.1107/S1600576720015344
SN  - 0021-8898
SN  - 1600-5767
VL  - 54
SP  - 228
EP  - 236
PB  - Munksgaard
CY  - Copenhagen
ER  -