Advances in Residual Stress Modelling and Simulation

eccentric holes in the determination of non-uniform residual stresses by the hole drilling strain gage method. Materials & Design. 2017;**132**:302-313. DOI: 10.1016/j.matdes.2017.06.051

*New Challenges in Residual Stress Measurements and Evaluation*

[21] Nobre JP, Kornmeier M, Scholtes B. Plasticity effects in the hole-drilling residual stress measurement in peened surfaces. Experimental Mechanics. 2018;**58**:369. DOI: 10.1007/s11340-017-

[22] Beghini M, Santus C, Valentini E, Benincasa A. Experimental verification of the hole drilling plasticity effect correction. Materials Science Forum. 2011;**681**:151-158. DOI: 10.4028/www.

scientific.net/MSF.681.151

[23] JCGM 100. Evaluation of measurement data—Guide to the expression of uncertainty in measurement. ISO/IEC Guide 98-3.

[24] Schajer GS, Altus EE. Stress calculation error analysis for

incremental hole-drilling residual stress measurements. ASME Journal of Engineering Materials and Technology. 1996;**118**(1):120-126. DOI: 10.1115/

[25] Oettel R. The determination of uncertainties in residual stress measurement (using the hole drilling technique). Code of Practice. EU Project No. SMT4-CT97-2165. Sept. 2000;**15**(1)

[26] Scafidi M, Valentini E, Zuccarello B. Error and uncertainty analysis of the residual stresses computed by using the hole drilling method. Strain. 2011;**47**: 301-312. DOI: 10.1111/j.1475-1305.

[27] Peral D, de Vicente J, Porro JA, Ocaña JL. Uncertainty analysis for nonuniform residual stresses determined by the hole drilling strain gage method. Measurement. 2017;**97**:51-63. ISSN: 0263-2241. DOI: 10.1016/j.measurement.

0352-5

2008

1.2805924

2009.00688.x

2016.11.010

[15] Abraham C, Schajer GS. Holedrilling residual stress measurement in an intermediate thickness specimen. In: Experimental and Applied Mechanics. Vol. 4. Conference Proceedings of the Society for Experimental Mechanics Series. New York, NY: Springer; 2013. Available from: https://doi.org/10.1007/

978-1-4614-4226-4\_46

[16] Beghini M, Bertini L, Giri A, Santus C, Valentini E. Measuring residual stress in finite thickness plates using the hole-drilling method. The Journal of Strain Analysis for

Engineering Design. 2019;**54**(1):65-75. DOI: 10.1177/0309324718821832

[17] Scafidi M, Valentini E, Zuccarello B. Effect of the hole-bottom fillet radius on the residual stress analysis by the hole drilling method. In: ICRS-8 The 8th International Conference on Residual Stress; Denver. 2008. pp. 263-270

[18] Simon N, Gibmeier J. Consideration of tool chamfer for realistic application of the incremental hole-drilling method. Materials Research Proceedings. 2017;**2**:

[19] Blödorn R, Bonomo L, Viotti M, Schroeter R, Albertazzi A Jr. Calibration coefficients determination through FEM simulations for the hole-drilling method considering the real hole geometry. Experimental Techniques. 2017;**41**:37. DOI: 10.1007/s40799-016-0152-3

[20] Beghini M, Bertini L, Santus C. A procedure for evaluating high residual stresses using the blind hole drilling method, including the effect of

plasticity. The Journal of Strain Analysis for Engineering Design. 2010;**45**(4): 301-318. DOI: 10.1243/03093247JSA579

**84**

473-478. DOI: 10.21741/ 9781945291173-80

**Chapter 5**

**Abstract**

*Heng Liu and Frank Liou*

and manufacturing parameters.

analysis, experimental validation

**1.1 Laser-aided direct metal deposition**

**1. Introduction**

**87**

Residual Stress Modeling and

Deformation Measurement in

Laser Metal Deposition Process

Direct metal deposition (DMD) has become very popular within the space of rapid manufacturing and repair. Its capability of producing fully dense metal parts with complex internal geometries, which could not be easily achieved by traditional manufacturing approaches, has been well demonstrated. However, the DMD process usually comes with high thermal gradients and high heating and cooling rates, leading to residual stresses and the associated deformation, which can have negative effect on product integrity. This paper studies the features of thermal stress and deformation involved in the DMD process by constructing a 3-D, sequentially coupled, thermomechanical, finite element model to predict both the thermal and mechanical behaviors of the DMD process of Stainless Steel 304 (SS 304). A set of experiments were then conducted to validate deformation using a laser displacement sensor. Comparisons between the simulated and experimental results show good agreement. This model can be used to predict the mechanical behavior of products fabricated by the DMD process and to help with the optimization of design

**Keywords:** additive manufacturing, residual stress, deformation, finite element

Laser-aided direct metal deposition (DMD) is an advanced additive

manufacturing (AM) technology which can produce fully dense, functional metal parts directly from CAD model. In its operation, the laser beam is focused onto a metallic substrate to create a melt pool, and a powder stream is continuously transported into the melt pool by the powder delivery system. The substrate is attached to a computer numerical control (CNC) multi-axis system, and by moving the substrate according to the desired route pattern, a 2-D layer can be deposited. By building successive layers on top of one another (layer by layer), a 3-D object can be formed. The DMD process has demonstrated its ability in the area of rapid manufacture, repair, and modification of metallic components. Practically, this process is most suitable for components with complex internal geometries that cannot be fabricated by traditional manufacturing methods such as casting.
