The effect of interface debonding on flexural behaviour of composite sandwich beams

2018 ◽  
Vol 22 (4) ◽  
pp. 1132-1156 ◽  
Author(s):  
Mohsen Mansourinik ◽  
Fathollah Taheri-Behrooz
Keyword(s):  
Cohesive Zone Model ◽  
Sandwich Beam ◽  
Interface Debonding ◽  
Zone Model ◽  
Nonlinear Behaviour ◽  
Loading Capacity ◽  
Sandwich Beams ◽  
Failure Initiation ◽  
The Core ◽  
Composite Skins

In the current article, the behaviour of sandwich beams with and without initial core–skin debonding is studied under flexural loads through numerical and experimental procedures. Sandwich beams with three different lengths of 100, 180 and 280 mm and two types of composite skin layups of [0/90]2 and [45/–45]2 are fabricated. An initial artificial debonding is created between core and face sheets during manufacturing the flawed sandwich beams. Numerical simulations and experiments of the short- and medium-sized intact beams revealed that the dominant failure mode is foam yielding and crushing. Thus, the composite skins layup sequence has almost no effect on the failure initiation and growth of those beams. However, in the long-sized sandwich beams, the layup sequence changed the load–displacement response of the beams. Moreover, ignoring the nonlinear behaviour of the composite skins caused a remarkable deviation from the experiment. It is shown that sandwich beams with initial debonding placed in tension side had a negligible effect on the loading capacity of the beams, while those on the compression side had remarkable effects. For instance, the ultimate load of the long-sized beam decreased by 56% compared to the intact sandwich beam. Similarly, in the medium-sized beam, the core–skin debonding in the compressive side caused near 20% reduction in the loading capacity compared to the corresponding intact beam. The cohesive zone model and the extended finite element method were utilized successfully to capture crack initiation and propagation between the core–skin interfaces as well as inside the foam core. Acceptable agreement was observed between the experiment and numerical results.

The Research of the Effective Moduli of Particle Reinforced Polymer Composites Based on Interface Debonding

2009 ◽  
Vol 413-414 ◽  
pp. 211-217
Author(s):  
Xin Long Chang ◽  
Bin Jian ◽  
Chang Ouyang
Keyword(s):  
Polymer Composites ◽  
Cohesive Zone Model ◽  
Volume Fraction ◽  
Micromechanical Model ◽  
Interface Debonding ◽  
Zone Model ◽  
Effective Moduli ◽  
Reinforced Polymer ◽  
The Matrix ◽  
Particulate Size

This paper is devoted to studying influences of matrix/particle interface debonding and particulate size in micromechanical predictions of the effective moduli of particulate reinforced polymer composites (PRPC). The PRPC is regarded as a three-phase composite that includes the matrix, particle and interphase. The formulation for the effective moduli of the interphase is derived by the cohesive zone model, and combined with the Mori-Tanaka method, the micromechanical model for the effective moduli of the PRPC is formulated with emphasis on the effects of the matrix/particle interface, particulate size and volume fraction. The numerical example shows that the interface debonding, the particulate size and volume fraction have significant influences on the effective moduli of PRPC. The effective moduli of the PRPC can be used to characterize its damage degree.

scholarly journals Simplified analytical model for tapered sandwich beams using variable stiffness materials

2016 ◽  
Vol 19 (1) ◽  
pp. 3-25 ◽  
Author(s):  
Qing Ai ◽  
Paul M Weaver
Keyword(s):  
Sandwich Beam ◽  
Shear Deformation Theory ◽  
Variable Stiffness ◽  
Axial Stiffness ◽  
Beam Model ◽  
Sandwich Beams ◽  
Element Analysis ◽  
The Core ◽  
The Face ◽  
Potential Energy Method

A simplified layer-wise sandwich beam model to capture the effects of a combination of geometric taper and variable stiffness of the core on the static response of a sandwich beam is developed. In the present model, the face sheets are assumed to behave as Euler beams and the core is modelled with a first-order shear deformation theory. With geometrical compatibility enforced at both upper and lower skin/core interfaces, the beam’s field functions are reduced to only three, namely the extensional, transverse and rotational displacements at the mid-plane of the core. The minimum total potential energy method is used in combination with the Ritz technique to obtain an approximate solution. Geometrically nonlinear effects are considered in the present formulation by introducing von Kármán strains into the face sheets and core. Two types of sandwich beams, uniform and tapered, with different boundary conditions are studied. Results show that the proposed model provides accurate prediction of displacements and stresses, compared to three-dimensional finite element analysis. It is found that due to the axial stiffness variation in the core, displacements of beams and stresses of face sheets and core are significantly affected. The potential design space is shown to be expanded by utilizing variable stiffness materials in sandwich constructions.

scholarly journals Modelling Microstructural Deformation and the Failure Process of Plastic Bonded Explosives Using the Cohesive Zone Model

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3661 ◽  
Author(s):  
Kaida Dai ◽  
Baodi Lu ◽  
Pengwan Chen ◽  
Jingjing Chen
Keyword(s):  
Mechanical Behavior ◽  
Cohesive Zone ◽  
Shear Failure ◽  
Cohesive Zone Model ◽  
Failure Process ◽  
Interface Debonding ◽  
Zone Model ◽  
Strain Rates ◽  
Cohesive Elements ◽  
Failure Evolution

A microstructure finite element method combining the cohesive zone model (CZM) is used to simulate the mechanical behavior, deformation, and failure of polymer-bonded explosive (PBX) 9501 under quasi-static loading. PBX 9501 consists of Cyclotetramethylene tetranitramine (HMX) filler particles with a random distribution packaged in a polymeric binder. The particle is treated as elastic and the binder as viscoelastic. Cohesive elements with a bilinear softening law are inserted into the particle/binder interface, the HMX particle, and the binder to study the interface’s debonding and failure evolution. Macroscopic stress–strain curves homogenized across the microstructure under tension and compression with different strain rates are basically consistent with the experimental data. The interface debonding approximately vertical to the loading direction is the primary failure mechanism under tension, while shear failure along the interfaces and particle fracture plays a significant role under compression. The effects of interface strengths and strain rates on the performance of PBX 9501 are also evaluated. The tensile and compressive strengths are dependent on the interface strength and strain rate, but the failure paths are insensitive. This model is shown to accurately predict macroscopic responses and improve our understanding of the relationship between the mechanical behavior and microstructure of PBX 9501.

Static Response of Stiff-Cored Unsymmetric Sandwich Beams

1976 ◽  
Vol 98 (2) ◽  
pp. 391-396 ◽  
Author(s):  
D. K. Rao
Keyword(s):  
Variational Method ◽  
Flexural Rigidity ◽  
Sandwich Beam ◽  
Sandwich Beams ◽  
Static Response ◽  
Simply Supported ◽  
The Core ◽  
Distributed Load ◽  
Very High ◽  
Maximum Stresses

Improved equations governing the deflection of an unsymmetric sandwich beam (which include the effect of extensional and bending rigidities of its stiff core) are derived using a variational method. The effect of face-thickness ratio on the contribution of the core to the overall flexural rigidity is studied. Numerical results for simply supported and fixed-fixed beams subjected to a uniformly distributed load are obtained by using Laplace transforms. These results show that ignoring the bending and extensional effects of a stiff core can cause errors in maximum deflections as high as 20 percent. The corresponding errors in stresses are very high, and they vary from 10 to 150 percent. Hence, it is suggested that the extensional and bending effects of the core should be taken into account when one is interested in calculating the maximum stresses in stiff-cored beams.

scholarly journals Flexural Response of Degraded Polyurethane Foam Core Sandwich Beam with Initial Crack between Facesheet and Core

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5399
Author(s):  
Gurpinder Singh Dhaliwal ◽  
Golam M. Newaz
Keyword(s):  
Loading Rate ◽  
Peak Load ◽  
Sandwich Beam ◽  
Initial Crack ◽  
Flexural Behavior ◽  
Sandwich Beams ◽  
Damage Initiation ◽  
The Core ◽  
Flexural Response ◽  
Core Thickness

Structural systems developed from novel materials that are more durable and less prone to maintenance during the service lifetime are in great demand. Due to many advantages such as being lightweight as well as having high strength, corrosion resistance, and durability, the sandwich composites structures, in particular, have attracted attention as favorable materials for speedy and durable structural constructions. In the present research, an experimental investigation is carried out to investigate the flexural response of sandwich beams with a pre-cracked core-upper facesheet interface located at one end of the beam. During the development of the sandwich beams, an initial pre-cracked debond was created between the core and facesheet by placing a Teflon sheet at the interface. Both three-point and four-point flexural tests were conducted to characterize the flexural behavior of the sandwich beams. The effects of the loading rate, core thickness, and placement of the initial interfacial crack under a compressive or tensile stress state on the response and failure mechanism of Carbon Fiber-Reinforced Polymer (CFRP)/Polyurethane (PU) foam sandwich beams were investigated. It was found that the crack tip of the initial debonding between the upper facesheet and the core served as a damage initiation trigger followed by the fracture failure of the core due to the growth of the initial crack into the core in an out-of-plane mode. Finally, this leads to facesheet damage and rupture under flexural loadings. An increase in the core thickness resulted in a higher peak load, but the failure of the sandwich beam was observed to occur at significantly lower displacement values. It was found that the behavior of sandwich beams with higher core thickness was loading rate-sensitive, resulting in stiffer response as the loading rate was increased from 0.05 to 1.5 mm/s. This change in stiffness (10–15%) could be related to the squeezing of all pore space, resulting in the collapse of cell walls and thereby making the cell behave as a solid material. As a result, the occurrence of the densification phase in thick core beams occurs at a faster rate, which in turn makes the thick cored sandwich beams exhibit loading rate-sensitive behavior.

scholarly journals The Mechanical Mechanism and Influencing Factors of Ice Adhesion Strength on Ice-Phobic Coating

2021 ◽  
Vol 9 (3) ◽  
pp. 315
Author(s):  
Qiang Xie ◽  
Tianhui Hao ◽  
Chao Wang ◽  
Zhenhang Kang ◽  
Zhonghua Shi ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Polymer Network ◽  
Three Dimensional ◽  
Interpenetrating Polymer Network ◽  
Interface Debonding ◽  
Zone Model ◽  
Ice Accretion ◽  
Elastic Film

Ice accretion can cause problems on polar ships, ocean platforms, and in other marine industries. It is important to understand the interface debonding behavior between ice and the surface of equipment. In this work, we created a mechanical model to analyze the interface debonding behavior between a square-based ice cuboid and an elastic coating base, using contact mechanics and fracture mechanics. Three-dimensional (3D) finite element (FE) simulation was used to simulate the interface debonding for normal and shear separation. A bilinear cohesive zone model (CZM) was used to simulate the interface between the ice cuboid and the elastic coating. We investigated the effect of the elastic modulus E of an elastic film on the critical detachment force Fc for normal and shear separation. The results showed that Fc increases with an increase of the elastic modulus of the elastic film. When E exceeds a certain level, Fc achieves a constant value and then remains stable. Finally, a series of epoxy/polydimethylsiloxane (PDMS) interpenetrating polymer-network (IPN) gel coatings with different elastic moduli were prepared. The ice tensile and shear adhesion strengths (σice and τice) of the coatings were measured. The results were roughly consistent with the results of the numerical simulation when E < 1 MPa.

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