Residual stresses are detrimental to composite structures as they induce processing defects like debonding, delamination, and matrix cracking which significantly decrease their load-bearing capability. In this research, a new in-situ approach using digital image correlation is utilized to analyze the effect of the cure cycle modification on residual stress evolution during processing. It was found that the modified cure cycle comprising abrupt cooling after gelation reduces the residual stresses. Five different layup configurations are investigated to examine the effect of fiber direction. A maximum average residual stress reduction of 31.8% is observed for the balanced unsymmetric [30/-30/60/-60] laminate. The residual stress reduction results in an increase in failure strength between 4 and 12% in the different layups and can lead up to a 22% increase in first-ply failure strength.
FuchsEFieldFRothR, et al.Strategic materials selection in the automobile body: economic opportunities for polymer composite design. Compos Sci Technol2008; 68: 1989–2002.
2.
PendhariSSKantTDesaiYM. Application of polymer composites in civil construction: a general review. Compos Struct2008; 84: 114–124.
3.
HeslehurstRB. Defects and Damage in Composite Materials and Structures. London, NY: CRC Press, 2014.
4.
NawabYJacqueminFCasariPet al.Study of variation of thermal expansion coefficients in carbon/epoxy laminated composite plates. Compos B Eng2013; 50: 144–149.
5.
ParlevlietPPBerseeHENBeukersA. Residual stresses in thermoplastic composites-A study of the literature-Part I: formation of residual stresses. Compos A Appl Sci Manuf2006; 37: 1847–1857.
6.
WangT-MDanielIMGotroJT. Thermoviscoelastic analysis of residual stresses and warpage in composite laminates. J Compos Mater1992; 26: 883–899.
7.
WisnomMRGigliottiMErsoyN, et al.Mechanisms generating residual stresses and distortion during manufacture of polymer-matrix composite structures. Compos A Appl Sci Manuf2006; 37: 522–529.
8.
ZhuQGeubellePHLiM, et al.Dimensional accuracy of thermoset composites: simulation of process-induced residual stresses. J Compos Mater2001; 35: 2171–2205.
9.
NairnJA. Matrix microcracking in composites. Compr Compos Mater2000; 2: 403–432.
10.
ZubillagaLTuronARenartJ, et al.An experimental study on matrix crack induced delamination in composite laminates. Compos Struct2015; 127: 10–17.
11.
PagliaroPZuccarelloB. Residual stress analysis of orthotropic materials by the through-hole drilling method. Exp Mech2007; 47: 217–236.
12.
ErsoyNVardarO. Measurement of residual stresses in layered composites by compliance method. J Compos Mater2000; 34: 575–598.
13.
CowleyKDBeaumontPWR. The measurement and prediction of residual stresses in carbon-fibre/polymer composites. Compos Sci Technol1997; 57: 1445–1455.
14.
JannottiPSubhashGZhengJ, et al.Measurement of microscale residual stresses in multi-phase ceramic composites using Raman spectroscopy. Acta Materialia2017; 129: 482–491.
15.
NairnJAZollerP. Matrix solidification and the resulting residual thermal stresses in composites. J Mater Sci1985; 20: 355–367.
16.
DuquennoyMOuaftouhMOurakM. Ultrasonic evaluation of stresses in orthotropic materials using Rayleigh waves. NDT E Int1999; 32: 189–199.
TuloupCHariziWAbouraZ, et al.On the use of in-situ piezoelectric sensors for the manufacturing and structural health monitoring of polymer-matrix composites: a literature review. Compos Struct2019; 215: 127–149.
19.
DoyleCMartinALiuT, et al.In-situprocess and condition monitoring of advanced fibre-reinforced composite materials using optical fibre sensors. Smart Mater Struct1998; 7: 145–158.
20.
WangGWangYZhangP, et al.Structure dependent properties of carbon nanomaterials enabled fiber sensors for in situ monitoring of composites. Compos Struct2018; 195: 36–44.
21.
HuangsZM. Strength formulae of unidirectional composites including thermal residual stresses. Mater Lett2000; 43: 36–42.
22.
ShokriehMMSafarabadiM. Three-dimensional analysis of micro-residual stresses in fibrous composites based on the energy method: a study including interphase effects. J Compos Mater2012; 46: 727–735.
23.
ZhaoLGWarriorNALongAC. A micromechanical study of residual stress and its effect on transverse failure in polymer-matrix composites. Int J Sol Struct2006; 43: 5449–5467.
24.
ShahPHallsVZhengJ, et al.Optimal cure cycle parameters for minimizing residual stresses in fiber-reinforced polymer composite laminates. J Compos Mater2018; 52: 773–792.
25.
AgboCOOkorieBAObikweluDO. Control of stress relaxation and residual thermal stress during cure of random fibre mat-reinforced polyester composites. J Compos Mater2017; 51: 3127–3136.
26.
KimSSMurayamaHKageyamaK, et al.Study on the curing process for carbon/epoxy composites to reduce thermal residual stress. Compos A Appl Sci Manuf2012; 43: 1197–1202.
27.
PrussakRStefaniakDKappelE, et al.Smart cure cycles for fiber metal laminates using embedded fiber Bragg grating sensors. Composite Structures2019; 213: 252–260.
28.
CrastoASKimRY. On the determination of residual stresses in fiber-reinforced thermoset composites. J Reinf PlastCompos1993; 12: 545–558.
29.
KimRYHahnHT. Effect of curing stresses on the first ply-failure in composite laminates. J Compos Mater1979; 13: 2–16.
30.
KamTYSherHF. Nonlinear and first-ply failure analyses of laminated composite cross-ply plates. J Compos Mater1995; 29: 463–482.
31.
ChavaSNamilaeS, 2021. In situ investigation of the kinematics of ply interfaces during composite manufacturing. J Manuf Sci Eng; 143: 021006. DOI: 10.1115/1.4047740.
32.
KimHSLeeDG. Avoidance of fabricational thermal residual stresses in co-cure bonded metal-composite hybrid structures. J Adhes Sci Technol2006; 20: 959–979.
33.
HardisRJessopJLPPetersFE, et al.Cure kinetics characterization and monitoring of an epoxy resin using DSC, Raman spectroscopy, and DEA. Compos A Appl Sci Manuf2013; 49: 100–108.
34.
MotagiSNamilaeS. In-situ investigation of resin shrinkage in the composite manufacturing environment. Appl Compos Mater2021; 28: 651–657.
35.
BowlesDETompkinsSS. Prediction of coefficients of thermal expansion for unidirectional composites. J Compos Mater1989; 23: 370–388.
36.
ChavaSNamilaeS. Continuous evolution of processing induced residual stresses in composites: an in-situ approach. Compos A Appl Sci Manuf2021; 145: 106368.
37.
IfjuPGNiuXKildayBC, et al.Residual strain measurement in composites using the cure-referencing method. Exp Mech2000; 40: 22–30.
38.
KimH-SYooS-HChangS-H. In situ monitoring of the strain evolution and curing reaction of composite laminates to reduce the thermal residual stress using FBG sensor and dielectrometry. Compos B Eng2013; 44: 446–452.
39.
HubertPFernlundGPoursartipA. Autoclave processing for composites. In: Manufacturing Techniques for Polymer Matrix Composites (PMCs). Cambridge: Elsevier, 2012, pp. 414–434.
40.
PalmeseGRMcCulloughRL. Kinetic and thermodynamic considerations regarding interphase formation in thermosetting composite systems. J Adhes1994; 44: 29–49.
41.
KimHSParkSWLeeDG. Smart cure cycle with cooling and reheating for co-cure bonded steel/carbon epoxy composite hybrid structures for reducing thermal residual stress. Compos A Appl Sci Manuf2006; 37: 1708–1721.
42.
KoyamaMHattaHFukudaH. Effect of temperature and layer thickness on these strengths of carbon bonding for carbon/carbon composites. Carbon2005; 43: 171–177.
43.
SoohyunNDongyoungLIlbeomC, et al.Smart cure cycle for reducing the thermal residual stress of a co-cured E-glass/carbon/epoxy composite structure for a vanadium redox flow battery. Compos Struct2015; 120: 107–116.
44.
StrongAB. Fundamentals of Composites Manufacturing: Materials, Methods and Applications. Dearborn, Mich: Society of Manufacturing Engineers, 2008.
45.
DanielIMIshaiODanielIM, et al.Engineering Mechanics of Composite Materials. New York: Oxford University Press, 2006.
46.
AgiusSLJoostenMTrippitB, et al.Rapidly cured epoxy/anhydride composites: effect of residual stress on laminate shear strength. Compos A Appl Sci Manuf2016; 90: 125–136.
