Isolation of residual shear stress effects in slitting measurement of residual normal stress in laminated composites

Abstract

The conventional strain gauge slitting method is usually used to determine the residual stress component normal to the slit plane. Therefore, it is assumed that residual shear stresses released in the slit plane have no effect on the released strains measured by strain gauge. This assumption is valid when measuring released strains by back surface strain gauges. However, in the top surface measurements, it is not true and neglecting residual shear stresses could create a biased estimation of residual normal stresses. In this research, a method based on the use of two symmetrically-placed strain gauges is proposed to separate the measured strains due to residual shear stresses from those due to residual normal stresses in the slitting method. In order to validate the proposed method, two series of slitting experiments were carried out on angle-ply carbon/epoxy laminated composites. The near-surface residual normal stresses were measured using the proposed method. These stresses were also determined using strain data obtained from the back surface strain gauge. Results of both experiments showed good agreement and thus verified the validity of the proposed method for the elimination of residual shear stresses effects in the slitting method.

Keywords

Slitting method residual normal stress residual shear stress laminated composites

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References

Schajer

. Relaxation methods for measuring residual stresses: techniques and opportunities. Exp Mech 2013; 50(8): 1117–1127.

Ersoy

Vardar

. Measurement of residual stresses in layered composites by compliance method. J Compos Mater 2000; 34(7): 575–598.

Eijpe

MPIM

Powell

. Residual stress evaluation in composites using a modified layer removal method. Compos Struct 1997; 37(3–4): 335–342.

Schajer

. Advances in hole-drilling residual stress measurements. Exp Mech 2013; 50(2): 159–168.

Sicot

Gong

Cherouat

. Determination of residual stress in composite laminates using the incremental hole-drilling method. J Compos Mater 2003; 37(9): 831–844.

Schajer

. Residual stress determination using cross-slitting and dual-axis ESPI. Exp Mech 2013; 50(2): 169–177.

Cheng

Finnie

. A method for measurement of axisymmetric residual stresses in circumferentially welded thin-walled cylinders. J Eng Mater Technol 1985; 107: 181–185.

Cheng

Finnie

. Measurement of residual hoop stress in cylinders using the compliance method. J Eng Mater Technol 1986; 108: 87–92.

Shokrieh

Akbari

. Effect of residual shear stresses on released strains in isotopic and orthotropic materials measured by the slitting method. J Eng Mater Technol 2013; 134(1): art. no. 011006.

10.

Lee

Hill

. Intralaboratory repeatability of residual stress determined by the slitting method. Exp Mech 2007; 47(6): 745–752.

11.

Prime

. Plasticity effects in incremental slitting measurement of residual stresses. Eng Fract Mech 2013; 77: 1552–1566.

12.

Schajer

. Measurement of non-uniform residual stresses using the hole-drilling method, Part I: stress calculation procedures. J Eng Mater Technol 1988; 110(4): 338–343.

13.

Prime

. Residual stress measurement by successive extension of a slot: the crack compliance method. J Appl Mech 1999; 52(2): 75–96.

14.

Cheng

Finnie

. Estimation of residual stresses. In: Frederick

F Ling

(ed) Residual stress measurement and the slitting method, USA: Springer, 2013, pp. 82–87.

15.

Shokrieh MM and Akbari RS. Simulation of slitting method for calculation of compliance functions of laminated composites. J Compos Mater 2011; 46(9): 1101–1109.

16.

Schajer

Prime

. Residual stress solution extrapolation for the slitting method using equilibrium constraints. J Eng Mater Technol 2007; 129: 227–232.

17.

Hosseinzadeh

Bouchard

James

. Measurements of residual stress in a welded compact tension specimen using the neutron diffraction and slitting techniques. Mater Sci Forum 2013; 652: 210–215.

18.

ANSYS Help System, Analysis Guide and Theory Reference, Ver. 12, 2009.

19.

Schajer

. Use of displacement data to calculate strain gauge response in non- uniform strain fields. Strain 1993; 29: 9–13.

20.

Schajer

Rickert

. Incremental computation technique for residual stress calculations using the integral method. Exp Mech 2013; 50(8): 1117–1127.

21.

Schajer

Altus

. Stress calculation error analysis for incremental hole-drilling residual stress measurements. J Eng Mater Technol 1996; 118: 120–126.