Modelling and computation until final fracture of laminate composites

Polyetheretherketone (PEEK) is a crystallizable thermoplastic used as composite matrix materials in application which requires high yield stress, high toughness, long term high temperature service, and resistance to solvent and radiation. There have been several reports on the crystallization behavior of neat PEEK and of CF/PEEK composite. Other reports discussed the effects of crystallization on the mechanical properties of PEEK and CF/PEEK composites. However, these reports were all concerned with the crystallization or melting processes at or close to atmospheric pressure. Thus, the effects of high pressure on the crystallization of CF/PEEK will be examined in this study.The continuous carbon fiber reinforced PEEK (CF/PEEK) laminate composite with 68 wt.% of fibers was obtained from Imperial Chemical Industry (ICI). For the high pressure experiments, HIP was used to keep these samples under 1000, 1500 or 2000 atm. Then the samples were slowly cooled from 420 °C to 60 °C in the cooling rate about 1 - 2 degree per minute to induce high pressure crystallization. After the high pressure treatment, the samples were scanned in regular DSC to study the crystallinity and the melting temperature. Following the regular polishing, etching, and gold coating of the sample surface, the scanning electron microscope (SEM) was used to image the microstructure of the crystals. Also the samples about 25mmx5mmx3mm were prepared for the 3-point bending tests.

Download Full-text

Determination of the transverse shear stress in layered composites

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2020-86-2-44-53 ◽

2020 ◽

Vol 86 (2) ◽

pp. 44-53

Author(s):

Yu. I. Dudarkov ◽

M. V. Limonin

Keyword(s):

Shear Stress ◽

Transverse Shear ◽

Composite Beam ◽

Layered Composite ◽

Equivalent Model ◽

Shear Stresses ◽

Transverse Shear Stress ◽

Layered Composites ◽

Laminate Composites ◽

Transverse Shear Stresses

An engineering approach to estimation of the transverse shear stresses in layered composites is developed. The technique is based on the well-known D. I. Zhuravsky equation for shear stresses in an isotropic beam upon transverse bending. In general, application of this equation to a composite beam is incorrect due to the heterogeneity of the composite structure. According to the proposed method, at the first stage of its implementation, a transition to the equivalent model of a homogeneous beam is made, for which the Zhuravsky formula is valid. The transition is carried out by changing the shape of the cross section of the beam, provided that the bending stiffness and generalized elastic modulus remain the same. The calculated shear stresses in the equivalent beam are then converted to the stress values in the original composite beam from the equilibrium condition. The main equations and definitions of the method as well as the analytical equation for estimation of the transverse shear stress in a composite beam are presented. The method is verified by comparing the analytical solution and the results of the numerical solution of the problem by finite element method (FEM). It is shown that laminate stacking sequence has a significant impact both on the character and on the value of the transverse shear stress distribution. The limits of the applicability of the developed technique attributed to the conditions of the validity of the hypothesis of straight normal are considered. It is noted that under this hypothesis the shear stresses do not depend on the layer shear modulus, which explains the absence of this parameter in the obtained equation. The classical theory of laminate composites is based on the similar assumptions, which gives ground to use this equation for an approximate estimation of the transverse shear stresses in in a layered composite package.

Download Full-text

Observing progressive damage in carbon fiber epoxy laminate composites via 3D in-situ X-ray tomography

Engineering Fracture Mechanics ◽

10.1016/j.engfracmech.2021.107626 ◽

2021 ◽

pp. 107626

Author(s):

Alejandra M. Ortiz-Morales ◽

Imad Hanhan ◽

Jose Javier Solano ◽

Michael D. Sangid

Keyword(s):

Carbon Fiber ◽

Progressive Damage ◽

Laminate Composites ◽

X Ray ◽

Carbon Fiber Epoxy

Download Full-text

Fracture Toughness Testing and its Implications to Engineering Fracture Mechanics Analysis of Energy Pipelines

Volume 1: Pipeline and Facilities Integrity ◽

10.1115/ipc2018-78723 ◽

2018 ◽

Author(s):

Sergio Limon ◽

Peter Martin ◽

Mike Barnum ◽

Robert Pilarczyk

Keyword(s):

Fracture Toughness ◽

Fracture Mechanics ◽

Test Data ◽

Fracture Mode ◽

Fracture Process ◽

Fracture Behavior ◽

Fracture Initiation ◽

Fracture Toughness Testing ◽

Final Fracture ◽

Toughness Testing

The fracture process of energy pipelines can be described in terms of fracture initiation, stable fracture propagation and final fracture or fracture arrest. Each of these stages, and the final fracture mode (leak or rupture), are directly impacted by the tendency towards brittle or ductile behavior that line pipe steels have the capacity to exhibit. Vintage and modern low carbon steels, such as those used to manufacture energy pipelines, exhibit a temperature-dependent transition from ductile-to-brittle behavior that affects the fracture behavior. There are numerous definitions of fracture toughness in common usage, depending on the stage of the fracture process and the behavior or fracture mode being evaluated. The most commonly used definitions in engineering fracture analysis of pipelines with cracks or long-seam weld defects are related to fracture initiation, stable propagation or final fracture. When choosing fracture toughness test data for use in engineering Fracture Mechanics-based assessments of energy pipelines, it is important to identify the stage of the fracture process and the expected fracture behavior in order to appropriately select test data that represent equivalent conditions. A mismatch between the physical fracture event being modeled and the chosen experimental fracture toughness data can result in unreliable predictions or overly conservative results. This paper presents a description of the physical fracture process, behavior and failure modes that pipelines commonly exhibit as they relate to fracture toughness testing, and their implications when evaluating cracks and cracks-like features in pipelines. Because pipeline operators, and practitioners of engineering Fracture Mechanics analyses, are often faced with the challenge of only having Charpy fracture toughness available, this paper also presents a review of the various correlations of Charpy toughness data to fracture toughness data expressed in terms of KIC or JIC. Considerations with the selection of an appropriate correlation for determining the failure pressure of pipelines in the presence of cracks and long-seam weld anomalies will be discussed.

Download Full-text

Finite Element Analysis of the Hydro-Mechanical Punching Process

Materials Science Forum ◽

10.4028/www.scientific.net/msf.505-507.871 ◽

2006 ◽

Vol 505-507 ◽

pp. 871-876

Author(s):

Jong Hun Yoon ◽

Hoon Huh ◽

Yong Sin Lee ◽

Seung Soo Kim ◽

E.J. Kim ◽

...

Keyword(s):

Hydrostatic Pressure ◽

Ductile Fracture ◽

Sheet Material ◽

Middle Surface ◽

Initial Crack ◽

Fracture Criteria ◽

Element Analysis ◽

Final Fracture ◽

Ductile Fracture Criteria ◽

Punching Process

This paper investigates the characteristics of a hydro-mechanical punching process. The hydro-mechanical punching process is divided into two stages: the first stage is the mechanical half piercing in which an upper punch goes down before the initial crack is occurred; the second stage is the hydro punching in which a lower punch goes up until the final fracture is occurred. Ductile fracture criteria such as the Cockcroft et al., Brozzo et al. and Oyane et al. are adopted to predict the fracture of a sheet material. The index value of ductile fracture criteria is calculated with a user material subroutine, VUMAT in the ABAQUS Explicit. The hydrostatic pressure retards the initiation of a crack in the upper region of the blank and induces another crack in the lower region of the blank during the punching process. The final fracture zone is placed at the middle surface of the blank to the thickness direction. The result demonstrates that the hydro-mechanical punching process makes a finer shearing surface than the conventional one as hydrostatic pressure increases.

Download Full-text

Mechanical Behavior of 3-ply Cu-Ni-Zn/Cu-Cr/Cu-Ni-Zn Composite Plate Processed by Roll Bonding

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.813.43 ◽

2013 ◽

Vol 813 ◽

pp. 43-46

Author(s):

Hob Yung Kim ◽

Jae Sook Song ◽

Sun Ig Hong

Keyword(s):

Heat Treatment ◽

Composite Plate ◽

Strain Curve ◽

Composite Plates ◽

Aging Condition ◽

Stress Strain Curve ◽

Roll Bonding ◽

Final Fracture ◽

Heat Treated ◽

Peak Aging

3-ply Cu-Ni-Zn/Cu-Cr/Cu-Ni-Zn clad composite plates were prepared by roll bonding at 823K and their properties were characterized. No intermetallic compounds were observed at Cu-Ni-Zn/Cu-Cr interfaces in the as-rolled and heat-treated Cu/Ni-Zn/Cu-Cr/Cu-Ni-Zn clad plates. The strength of as-rolled clad plate reached up to 420MPa with the ductility of 13%. After heat treatment at 723K for 1.5 hours, the strength of Cu-Ni-Zn/Cu-Cr/Cu-Ni-Zn clad composite plate dropped to 340 MPa and the ductility increased to 20%. With annealing at 723K, there is no drastic drop of the stress before final fracture, meaning three plates were bonded together until the last part of the stress-strain curve. The peak of the conductivity (>70% of IACS) was attained after aging for 1.5 hrs, compatible with the typical peak aging condition of Cu-Cr alloy.

Download Full-text

Failure of metallic-intermetallic laminate composites under dynamic loading

10.1063/1.3686471 ◽

2012 ◽

Cited By ~ 9

Author(s):

Sergey Zelepugin ◽

Vyacheslav Mali ◽

Aleksej Zelepugin ◽

Elena Ilina

Keyword(s):

Dynamic Loading ◽

Laminate Composites

Download Full-text

Micro/Nano-Structural Transition and Hydrogen Absorption Mechanism in Mg/Cu Super-Laminate Composites

Journal of the Japan Institute of Metals and Materials ◽

10.2320/jinstmet.j2015034 ◽

2015 ◽

Vol 79 (12) ◽

pp. 644-650 ◽

Cited By ~ 1

Author(s):

Koji Tanaka ◽

Hiroyuki T. Takeshita ◽

Ho Shin ◽

Kosuke Kurumatani ◽

Tetsu Kiyobayashi ◽

...

Keyword(s):

Hydrogen Absorption ◽

Structural Transition ◽

Absorption Mechanism ◽

Laminate Composites

Download Full-text

Design of Alumina/Alumina Laminate Composites with Crystalline-Orientated Layers Produced by Electrophoretic Deposition under a High Magnetic Field

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.314.25 ◽

2006 ◽

Vol 314 ◽

pp. 25-32

Author(s):

Tetsuo Uchikoshi ◽

Tohru Suzuki ◽

Hideo Okuyama ◽

Yoshio Sakka

Keyword(s):

Magnetic Field ◽

Electrophoretic Deposition ◽

Orientation Angle ◽

Layer By Layer ◽

Alumina Ceramics ◽

X Ray Diffraction ◽

Laminate Composites ◽

Laminar Composites ◽

The Magnetic Field ◽

Oriented Layers

Highly crystalline-textured alumina ceramics were fabricated by electrophoretic deposition (EPD) in a strong magnetic field of 12 T. Preferred orientation of the bulk was controlled by changing the direction of the applied electric field E relative to the magnetic field B during the EPD. Average orientation angle of the prepared monoliths as a function of the angle between the vectors E and B, ϕ B-E was estimated from the X-ray diffraction analysis. Alumina/alumina laminar composites with crystalline- oriented layers were also fabricated by alternately changing the ϕ B-E layer by layer during EPD in a magnetic field of 12 T.

Download Full-text