The use of carbon nanofibers for thermal residual stress reduction in carbon fiber/epoxy laminated composites

Abstract Carbon nanofibers (CNFs) were incorporated into an epoxy matrix with three weight fractions of 0.1%, 0.5% and 1% which were then reinforced with unidirectional carbon fibers (CFs) to fabricate laminated composites with cross-ply configuration. Thermomechanical analysis and tensile tests of the specimens were carried out to characterize thermal and mechanical properties of CNF/epoxy composites and compare them with the behavior of the neat resin. Characterization showed that the coefficient of thermal expansion (CTE) of the epoxy matrix is significantly reduced by adding small amounts of CNF. CNFs also moderately increase the Young’s modulus of the epoxy. The slitting method was used for the measurement of residual stresses in cross-ply CF/epoxy and CNF-reinforced CF/epoxy laminates. It involves cutting a narrow slit progressively from one surface of the laminate, and measuring the released strains at the other surface. The results showed that the addition of 0.1%, 0.5% and 1 wt.% CNF leads to 4.4%, 18.8% and 25.1% reductions in residual stress, respectively. These findings confirm that CNFs possess excellent potential to be used as a thermal expansion compensator for the modification of the thermal behavior of the epoxy matrix and the reduction of the thermal residual stresses in the fiber/epoxy laminated composites.

[1]  T. Nishino,et al.  Residual stress of particulate polymer composites with reduced thermal expansion , 2009 .

[2]  Michael B. Prime,et al.  Residual Stress Measurement by Successive Extension of a Slot: The Crack Compliance Method , 1999 .

[3]  Bijan Mohammadi,et al.  Thermal residual stresses effects on fatigue crack growth of repaired panels bounded with various composite materials , 2009 .

[4]  M. Darby,et al.  Residual stresses and the optimum cure cycle for an epoxy resin , 1989 .

[5]  M. R. Hill,et al.  Residual Stress Measurement in a Ceramic-Metallic Graded Material , 2002 .

[6]  François Béguin,et al.  Mechanical properties of multiwall carbon nanotubes/epoxy composites: influence of network morphology , 2004 .

[7]  C. Smith,et al.  Tailored thermal expansivity in particulate composites for thermal stress management , 2008 .

[8]  I. Ward,et al.  The incorporation of carbon nanofibres to enhance the properties of self reinforced, single polymer composites , 2005 .

[9]  G. S. Schajer,et al.  Relaxation Methods for Measuring Residual Stresses: Techniques and Opportunities , 2010 .

[10]  Michael W. Hyer,et al.  Calculations of the Room-Temperature Shapes of Unsymmetric Laminatestwo , 1981 .

[11]  Meng-Kao Yeh,et al.  Mechanical behavior of phenolic-based composites reinforced with multi-walled carbon nanotubes , 2006 .

[12]  Harold E. Gascoigne,et al.  Residual surface stresses in laminated cross-ply fiber-epoxy composite materials , 1994 .

[13]  M. Shokrieh,et al.  Fabrication of Multi-Walled Carbon Nanotube/Vinyl Ester Nanocomposites: Dispersion and Stabilization , 2011 .

[14]  Michael B. Prime,et al.  RESIDUAL STRESS SOLUTION EXTRAPOLATION FOR THE SLITTING METHOD USING EQUILIBRIUM CONSTRAINTS , 2007 .

[15]  Michael R. Hill,et al.  Effect of Strain Gage Length When Determining Residual Stress by Slitting , 2007 .

[16]  Seung-Hwan Chang,et al.  In situ monitoring of the strain evolution and curing reaction of composite laminates to reduce the thermal residual stress using FBG sensor and dielectrometry , 2013 .

[17]  Bernardo Zuccarello,et al.  Optimal calculation steps for the evaluation of residual stress by the incremental hole-drilling method , 1999 .

[18]  Z. Ounaies,et al.  Preparation, characterization, and modeling of carbon nanofiber/epoxy nanocomposites , 2011 .

[19]  Ben Wang,et al.  Effect of Nanotube Functionalization on the Coefficient of Thermal Expansion of Nanocomposites , 2007 .

[20]  W. Zhong,et al.  Mechanical, thermal and morphological characterization of polycarbonate/oxidized carbon nanofiber composites produced with a lean 2-step manufacturing process. , 2011, Journal of nanoscience and nanotechnology.

[21]  Dai Gil Lee,et al.  Reduction of residual stresses in thick-walled composite cylinders by smart cure cycle with cooling and reheating , 2006 .

[22]  M. R. Kessler,et al.  Carbon fiber-reinforced cyanate ester/nano-ZrW2O8 composites with tailored thermal expansion. , 2012, ACS applied materials & interfaces.

[23]  S. Kim,et al.  Study on the curing process for carbon/epoxy composites to reduce thermal residual stress , 2012 .

[24]  Michael B. Prime,et al.  Use of Inverse Solutions for Residual Stress Measurements , 2006 .

[25]  Gary S. Schajer,et al.  Use of displacement data to calculate strain gauge response in non‐uniform strain fields , 1993 .

[26]  G. Wegner,et al.  Modifying thermal expansion of polymer composites by blending with a negative thermal expansion material , 2007 .

[27]  K. Takenaka.  Negative thermal expansion materials: technological key for control of thermal expansion , 2012, Science and technology of advanced materials.

[28]  S. White,et al.  Cure Cycle Optimization for the Reduction of Processing-Induced Residual Stresses in Composite Materials , 1993 .

[29]  Nuri Ersoy,et al.  Measurement of Residual Stresses in Layered Composites by Compliance Method , 2000 .

[30]  M. R. Hill,et al.  Intralaboratory Repeatability of Residual Stress Determined by the Slitting Method , 2007 .

[31]  Kuang-Ting Hsiao,et al.  Investigation on the spring-in phenomenon of carbon nanofiber-glass fiber/polyester composites manufactured with vacuum assisted resin transfer molding , 2008 .