**5. Conclusions**

−517 to −605 MPa, which is improved by 17%. The max CRS varies from −684 to −794 MPa and the increase rate is about 16%. It is mainly due to the improved shot velocity after increasing SP intensity, which can cause more severe plastic deformation on surface, the deeper surface deformation layer and the larger CRS. Comparing the results by simulation and experiment, it reveals that the variation trends of residual stress by simulation are similar with the results from experiment.

**Figure 16.** Depth distribution of CRS on the matrix and composite under three different SP intensities [36], (a) Ti-6Al-4V;

**Figure 15.** (a) Schematic figure of residual stress measurement coordinate; (b) photo of the residual stress measurement

**Figure 16(b)** shows the experimental results of residual stress distribution on the composite 8% (TiB+TiC)/Ti-6Al-4V. From the figure, the depths of surface deformation layer are 200, 250, and 300 μm corresponding to 0.15, 0.30, and 0.45 mmA, which are shallower than the matrix's. The difference is resulted from the existence of reinforcements' resistance to the deformation of surface. Moreover, SP intensity has direct relation to the shot velocity. The larger impact velocity, the higher impact kinetic energy, and the depths of surface deformation layer are deeper.

**4.3. Residual stress distribution of 8% (TiB+TiC)/Ti-6Al-4V**

42 Finite Element Method - Simulation, Numerical Analysis and Solution Techniques

using X-ray stress analyzer.

(b) 8% (TiB+TiC)/Ti-6Al-4V.

In order to study the effect of various parameters on the residual stress distribution after SP, LS/DYNA analysis module in ANSYS is utilized to establish the finite element model for Ti-6Al-4V and (TiB+TiC)/Ti-6Al-4V, and both 3D homogeneous and inhomogeneous models are set up. The influence of coverage rate, shot radius, and shot velocity on residual stress distribution is studied using the multi-layer shot balls to simulate the actual SP process. The main results are concluded as the following:


**5.** The results obtained from the inhomogeneous SP model reveal that the compressive and tensile residual stresses are introduced in (TiB+TiC)/Ti-6Al-4V. The max CRS and tensile residual stress are −1511 and +1155 MPa, respectively. CRS appear in matrix, but the tensile residual stresses gets generated in the reinforcements, which reveals the higher yield strength of reinforcements. This stress distribution indicates the effect of reinforcements, keeping the adverse tensile stresses in reinforcements and retarding the damage to matrix.

**References**

A. 2004;**382**:188-197

2011;**528**:5259-5263

2005

DGM, Citeseer. 2002. pp. 145-160

[1] Bruno G, Fernández R, Gonzalez-Doncel G. Relaxation of the residual stress in 6061Al-15 vol.% SiC w composites by isothermal annealing. Materials Science and Engineering

Finite Element Dynamic Analysis on Residual Stress Distribution of Titanium Alloy and Titanium…

http://dx.doi.org/10.5772/intechopen.73120

45

[2] Schulze V. Characteristics of surface layers produced by shot peening. In: Proceeding of the Eighth International Conference on Shot Peening ICSP-8 in Garmisch-Partenkirchen

[3] Kim K-H, Kim Y-C, Jeon E-C, Kwon D. Evaluation of indentation tensile properties of Ti alloys by considering plastic constraint effect. Materials Science and Engineering A.

[4] Benedetti M, Fontanari V, Monelli B. Numerical simulation of residual stress relaxation in shot peened high-strength aluminum alloys under reverse bending fatigue. Journal of

[5] Kim T, Lee JH, Lee H, Cheong S-k. An area-average approach to peening residual stress under multi-impacts using a three-dimensional symmetry-cell finite element model

[6] Prasannavenkatesan R, Zhang J, McDowell DL, Olson GB, Jou H-J. 3D modeling of subsurface fatigue crack nucleation potency of primary inclusions in heat treated and shot peened martensitic gear steels. International Journal of Fatigue. 2009;**31**:1176-1189

[7] Guagliano M. Relating Almen intensity to residual stresses induced by shot peening: A numerical approach. Journal of Materials Processing Technology. 2001;**110**:277-286

[8] Rouhaud E, Ouakka A, Ould C, Chaboche J, Francois M. Finite elements model of shot peening, effects of constitutive laws of the material, Proceedings ICSP-9, Paris, France.

[9] Ould C, Rouhaud E, François M, Chaboche JL. A kinematic hardening finite elements model to evaluate residual stresses in shot-peened parts, local measurements by X-ray

[10] Baragetti S, Guagliano M, Vergani L. A numerical procedure for shot peening optimisation by means of non-dimensional factors. International Journal of Materials and

[11] Boyce B, Chen X, Hutchinson J, Ritchie R. The residual stress state due to a spherical

[12] Evans R. Shot peening process: Modelling, verification, and optimisation. Materials

[13] Levers A.A. Prior, finite element analysis of shot peening. Journal of Materials Processing

diffraction. In: Mater. Sci. Forum Trans Tech Publ. 2006. pp. 161-166

hard-body impact. Mechanics of Materials. 2001;**33**:441-454

Product Technology. 2000;**15**:91-103

Science and Technology. 2002;**18**:831-839

Technology. 1998;**80**:304-308

Engineering Materials and Technology. 2010;**132**:011012

with plastic shots. Materials & Design. 2010;**31**:50-59

**6.** The experimental results from XRD method are shown that the surface CRS increased from −545 to −724 MPa and the max CRS varies from −655 to −819 MPa. The ranges of residual stress distribution in experiments are in good agreement with the simulated results by 3D finite element dynamic analysis.

From all results and discussion, using 3D finite element dynamic analysis to simulate the residual stress distribution of titanium matrix composite is reasonable, especially for the stress distribution in and around the reinforcements.
