scholarly journals Delamination Onset in Polymeric Composite Laminates Under Thermal and Mechanical Loads

2009 ◽  
pp. 39-39-27 ◽  
Author(s):  
RH Martin
Keyword(s):  
Composite Laminates ◽  
Polymeric Composite ◽  
Mechanical Loads

Damage Control in Composite Laminates

2001 ◽  
Author(s):  
Alexander P. Suvorov ◽  
George J. Dvorak
Keyword(s):  
Composite Laminates ◽  
Composite Laminate ◽  
Damage Control ◽  
Thermomechanical Loading ◽  
Interlaminar Stresses ◽  
Damage Resistance ◽  
Viscoelastic Composite ◽  
Mechanical Loads ◽  
Composite Damage ◽  
The Matrix

Abstract Several effects that fiber prestress may have on stress redistribution in the plies of composite laminates and in the phases of individual plies are illustrated. These include improvement of composite damage resistance under tensile mechanical loads, reduction/cancelation of interlaminar stresses at free edges of composite laminate subjected to thermomechanical loading, and stress relaxation in the matrix phase of viscoelastic composite laminates. Specific results are found for quasi-isotropic and cross-ply symmetric S-glass/epoxy and carbon/epoxy AS4/EPON 828 laminates.

Damage detection of unidirectional carbon fiber–reinforced laminates with embedded magnetostrictive particulates: A preliminary study

2012 ◽  
Vol 24 (8) ◽  
pp. 991-1006 ◽  
Author(s):  
Oliver J Myers ◽  
George Currie ◽  
Jonathan Rudd ◽  
Dustin Spayde ◽  
Nydeia Wright Bolden
Keyword(s):  
Composite Materials ◽  
Carbon Fiber ◽  
Nondestructive Evaluation ◽  
Composite Laminates ◽  
Composite Structures ◽  
Single Layer ◽  
Polymeric Composite ◽  
Analytical Models ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced

Defects in composite laminates are difficult to detect because of the conductive and paramagnetic properties of composite materials. Timely detection of defects in composite laminates can improve reliability. This research illustrates the preliminary analysis and detection of delaminations in carbon fiber laminate beams using a single layer of magnetostrictive particles and noncontacting concentric magnetic excitation and sensing coils. The baseline analytical models also begin to address the intrusive nature of the magnetostrictive particles as well as relate the applied excitation field with the stress and magnetic flux densities induced in the magnetostrictive layer. Numerical methods are used to begin to characterize the presence of magnetostrictive particles in the laminate and the behavior of the magnetostrictive particles in relationship to the magnetic field used during sensing. Unidirectional laminates with embedded delaminations are used for simulations and experimentations. A novel, yet simplified fabrication method is discussed to ensure consistent scanning and sensing capabilities. The nondestructive evaluation scanning experiments were conducted with various shapes and sizes of damages introduced into carbon fiber–reinforced polymeric composite structures. The results demonstrate high potential for magnetostrictive particles as a low-cost, noncontacting, and reliable sensor for nondestructive evaluation of composite materials.

scholarly journals Buckling and postbuckling behavior of shell type structures under thermo-mechanical loads

2021 ◽  
pp. 79-79
Author(s):  
Zoran Vasic ◽  
Katarina Maksimovic ◽  
Mirko Maksimovic ◽  
Ivana Vasovic ◽  
Nenad Vidanovic ◽  
...  
Keyword(s):  
Finite Element ◽  
Shear Deformation ◽  
Composite Laminates ◽  
Shear Deformation Theory ◽  
Higher Order ◽  
Thermal Buckling ◽  
Laminated Plates ◽  
Postbuckling Behavior ◽  
Mechanical Loads ◽  
Shell Type

The thermomechanical buckling and postbuckling behavior of layered composite shell type structure are considered with the finite element method (FEM) under the combination of temperature load and applied mechanical loads. To account for through-thickness shear deformation effects, the thermal elastic, Higher-Order Shear deformation Theory (HOST) is used in this study. The refined higher order theories, that takes into account the effect of transverse normal deformation, is used to develop discrete finite element models for the thermal buckling analysis of composite laminates. Attention in this study is focused on analyzing the temperature effects on buckling and postbuckling behavior of thin shell structural components. Special attention in this paper is focused on studying of values of the hole in curved panel on thermal buckling behavior and consequently to expend and upgrade previously conducted investigation. Using FEM, a broader observation of the critical temperature of loss of stability depending on the size of the hole was conducted. The presented numerical results based on HOST can be used as versatile and accurate method for buckling and postbuckling analyzes of thin-walled laminated plates under thermo-mechanical loads.

Physical Aging in Long Term Creep of Polymeric Composite Laminates

2007 ◽  
Vol 23 (3) ◽  
pp. 245-252 ◽  
Author(s):  
H. W. Hu
Keyword(s):  
Aging Time ◽  
Composite Laminates ◽  
Physical Aging ◽  
Creep Compliance ◽  
Polymeric Composite ◽  
Reference Curve ◽  
Creep Tests ◽  
Time Model ◽  
Term Creep

AbstractThis paper presents a complete approach to characterize physical aging in long term creep of composite laminates using short term creep test. Carbon/epoxy composite IM7/977−3 was use to make the coupon specimens of unidirectional fiber orientation and symmetrical laminates. Creep tests were conducted on the specimens to obtain momentary compliances at isothermal conditions. Physical aging in elastic and in creep compliances were modeled respectively. Momentary creep compliances in various aging times were shifted to superpose a reference curve by introducing shift factors for both relaxation time and shape factor of a power law model. Linear relations between shift factors and aging time in log-log scale were found and defined as shift rates. By using reference curve associated with the shift rates, momentary creep compliance in any given aging time can be predicted. By introducing a time dependent shift factor, momentary creep compliance can be modified and turned into an effective time model, which can successfully predict the long term creep of composite laminates at isothermal aging. This approach only requires the test data of momentary creep, and no material properties in each lamina are needed.

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