Evaluation of the Interfacial Strength of Layered Structures by Indentation Method

2008 ◽  
Vol 75 (3) ◽  
Author(s):  
Masaki Omiya ◽  
Kikuo Kishimoto ◽  
Takashi Nakano
Keyword(s):  
Evaluation Method ◽  
Cohesive Zone Model ◽  
Interfacial Strength ◽  
Layered Structures ◽  
Indentation Load ◽  
Zone Model ◽  
Coating Film ◽  
Coating Films ◽  
Indentation Tests ◽  
Depth Curve

The delamination of thin coating films from substrates is a critical issue for the reliability of micro- and nanoelectronic devices. Indentation methods have the potential to measure interfacial strength in micro- and nanofilm thickness coating films. In this paper, indentation tests of layered structures are simulated using the damage-based cohesive zone model. When the delamination initiates, the indentation load and depth curve tend to deviate from the indentation load and depth curve for the perfectly bonded case. When the interface is stiffer than the coating film, a brittlelike delamination occurs on the interface; when the stiffness of the interface is smaller than that of the coating layer, a ductilelike delamination occurs on the interface. The ratio of shear moduli, μint∕μPI, characterizes the delamination behavior on the interface during indentation tests. Focusing on the discontinuous point during the indentation tests and introducing the balance of energy before and after the onset of delamination, the evaluation method of the interfacial strength is proposed. The proposed method can be used to estimate the interfacial strength when the ratio of hardness and the yield stress of the coating film is 3.5<HA∕σy<4.5.

Interfacial Debonding and Stress Field Analysis on a Single Fiber Composite Using FEM

2008 ◽  
Author(s):  
Yi Pan ◽  
Assimina A. Pelegri
Keyword(s):  
Stress Field ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Fiber Composite ◽  
Interfacial Strength ◽  
Interfacial Debonding ◽  
Field Analysis ◽  
Zone Model ◽  
Linear Elastic ◽  
Bonded Composite

Fiber debonding in a bundled fiber reinforced polymer composite is investigated by using finite element method and cohesive zone model. Fiber and matrix are modeled as isotropic and linear elastic materials. Fiber/matrix interface is represented by a cohesive zone model governed by the traction-separation law. Effects of interfacial strength on interfacial debonding and stress field in the bundled fiber composite are examined. The stress field of the debonding composite is compared to that of perfectly bonded composite.

Peeling Rate Dependency of Delamination Behavior of Adhesives

2008 ◽  
Vol 33-37 ◽  
pp. 339-344 ◽  
Author(s):  
Ryota Masuda ◽  
Hirotsugu Inoue ◽  
Kikuo Kishimoto
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Cohesive Zone Model ◽  
Base Material ◽  
Interfacial Strength ◽  
Video Camera ◽  
Zone Model ◽  
Rate Dependency ◽  
Element Analysis ◽  
Rate Region

Adhesives are widely used in our life and industrial world. However, it is difficult to characterize their mechanical properties because those strongly depend on environmental and mechanical conditions such as temperature, humidity or strain rate. In this paper, we focus on the strain rate dependence of the interfacial strength and investigate the interfacial strength by peel tests under several peel rates. The results show that, in lower rate region (under 1.0 mm/s), the interfacial strength is constant and, in transition region (1.0 to 10 mm/s) the interface strength increased with the peel rate. In middle rate region (10 to 103 mm/s), the interfacial strength is constant again. Over 103 mm/s region, the interfacial strength drops and became lower than those in middle rate cases. From the observation of peeling front by a high speed video camera, the deformation behavior of adhesives changes with the peel rate.􀀁Finite element analysis by using cohesive zone model is also conducted, and influence of the rate dependency of adhesive and base material is discussed.

Estimating the Cohesive Zone Model Parameters of Carbon Nanotube–Polymer Interface for Machining Simulations

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Lingyun Jiang ◽  
Chandra Nath ◽  
Johnson Samuel ◽  
Shiv G. Kapoor
Keyword(s):  
Carbon Nanotube ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Interfacial Strength ◽  
Weight Fraction ◽  
Model Parameters ◽  
Zone Model ◽  
Fe Model ◽  
Polymer Interface ◽  
Two Parameters

The failure mechanisms encountered during the machining of carbon nanotube (CNT) polymer composites are primarily governed by the strength of the CNT–polymer interface. Therefore, the interface should be explicitly modeled in microstructure-level machining simulations for these composites. One way of effectively capturing the behavior of this interface is by the use of a cohesive zone model (CZM) that is characterized by two parameters, viz., interfacial strength and interfacial fracture energy. The objective of this study is to estimate these two CZM parameters of the interface using an inverse iterative finite element (FE) approach. A microstructure-level 3D FE model for nanoindentation simulation has been developed where the composite microstructure is modeled using three distinct phases, viz., the CNT, the polymer, and the interface. The unknown CZM parameters of the interface are then determined by minimizing the root mean square (RMS) error between the simulated and the experimental nanoindentation load–displacement curves for a 2 wt. % CNT–polyvinyl alcohol (PVA) composite sample at room temperature and quasi-static strain state of up to 0.04 s−1, and then validated using the 1 wt. % and 4 wt. % CNT–PVA composites. The results indicate that for well-dispersed and aligned CNT–PVA composites, the CZM parameters of the interface are independent of the CNT loading in the weight fraction range of 1–4%.

Study of Delamination of Thin Film Coating on Cyclic Nano-Indentation Test

2007 ◽  
Vol 353-358 ◽  
pp. 1842-1845 ◽  
Author(s):  
Kentaro Kozuki ◽  
Masaki Omiya ◽  
Kikuo Kishimoto ◽  
Hirotsugu Inoue
Keyword(s):  
Thin Film ◽  
Evaluation Method ◽  
Surface Profile ◽  
Indentation Test ◽  
Interfacial Strength ◽  
Peel Test ◽  
Indentation Load ◽  
Displacement Curve ◽  
Buckling Mode ◽  
Nano Indentation

The aim of this paper is to evaluate the cyclic interfacial strength between thin film and its substrate by cyclic nano-indentation tests. The specimen used in this study is PET substrate/ITO coatings layered specimen. From the indentation load and displacement curve, we proposed an evaluation method for the interfacial strength. The results are good agreement with the interfacial strength evaluated by peel test. After cyclic indentations, the surface profile was observed by atomic force microscope. The number of elongates increased with indentation cycles when the indentation load is low, whereas elongates number is almost constant under high load cases. These phenomena can be explained by simple models. In this study, two types of fracture modes are proposed. They are “subsidiary fracture mode” and “buckling mode”.

scholarly journals Influence of Fiber Distribution and Interfacial Strength on Transverse Compressive Strength of Unidirectional Composites

2019 ◽  
Vol 37 (3) ◽  
pp. 443-448
Author(s):  
Xiaopeng Wan ◽  
Guangmeng Yang ◽  
Meiying Zhao
Keyword(s):  
Compressive Strength ◽  
Cohesive Zone Model ◽  
Interfacial Strength ◽  
Interface Element ◽  
Zone Model ◽  
Fiber Distribution ◽  
Interfacial Damage ◽  
Unidirectional Composites ◽  
The Matrix ◽  
Damage Process

The representative volume element(RVE) of the computational micromechanics is established with random fiber distribution being generated by random sequential expansion algorithm. The plasticity of matrix and interfacial decohesion are simulated by using Drucker-Prager model and cohesive zone model respectively. The effects of the random fiber distribution and interfacial strength on the transverse compressive strength of unidirectional composites are analyzed. The results show that the random fiber distribution is a factor to cause the instability of the transverse compressive strength. Meanwhile, the matrix plastic shear damage and non interfacial damage is dominated in compression failure. Therefore, the RVE model without interface element adopted can clearly predict the compressive strength and the damage process of unidirectional composites, which contributes to simplify the modeling without considering the value of interfacial parameters.

Numerical Analysis on the Influence of Interface on the Mechanical Behavior of Unidirectional Fiber Composites under Different Loads

2013 ◽  
Vol 575-576 ◽  
pp. 188-193
Author(s):  
Peng Qu ◽  
Yu Xi Jia ◽  
Guo Wei Zhu ◽  
Yun Li Guo ◽  
Xiao Chen Sun
Keyword(s):  
Mechanical Behavior ◽  
Cohesive Zone Model ◽  
Interfacial Strength ◽  
Unidirectional Composite ◽  
Transverse Load ◽  
Failure Behavior ◽  
Zone Model ◽  
Failure Strength ◽  
Multi Scale ◽  
Representative Unit Cell

On the smallest structural scale in the multi-scale structure composites, namely fiber scale, a numerical model was proposed for the analysis on the mechanical properties of unidirectional composites through the representative unit cell (RUC). The progressive method was used to simulate the failure behavior of fiber and matrix, and the debonding between fiber and matrix was characterized by the cohesive zone model (CZM). The failure strength of the unidirectional composite was predicted, and the influence of the interfacial strength on the mechanical behavior of unidirectional composite was discussed. It is shown that fiber dominates the failure strength of the material under the longitudinal load, whereas under the transverse load interfacial properties play an important role in the mechanical behavior of the material. The increase of the interfacial strength can significantly improve the capability of transverse compression and shear resistance.

Estimating the Cohesive Zone Model Parameters for Carbon Nanotube–Polymer Interface Using Inverse Finite Element Approach

2012 ◽  
Author(s):  
Lingyun Jiang ◽  
Chandra Nath ◽  
Johnson Samuel ◽  
Shiv G. Kapoor
Keyword(s):  
Finite Element ◽  
Carbon Nanotube ◽  
Fracture Energy ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Interfacial Strength ◽  
Model Parameters ◽  
Zone Model ◽  
Displacement Curve ◽  
Polymer Interface

During machining of carbon nanotube (CNT)-polymer composites, the failure of the polymer elements occurs at the CNT-polymer interface. The interfacial behavior that can be represented by a cohesive zone model (CZM) is mainly influenced by two parameters, viz., interfacial strength and fracture energy. The objective of this study is to estimate these two specific CZM parameters using an inverse finite element (FE) simulation approach that works based on an iterative error minimization procedure. Nanoindentation tests have been conducted on a CNT-polyvinyl alcohol (PVA) composite sample containing 4 wt% multi-walled nanotubes (MWNTs). A 2D axisymmetric FE model of nanoindentation has been developed. This micro-structure based model considers the CNT, the PVA, and the cohesive zone of interface as three individual phases. The unknown interfacial parameters are determined by minimizing the error between the simulation load-displacement curve and the experimental results. The interfacial strength and the fracture energy at the CNT-PVA interface are estimated to be approximately 40 MPa and 16e−3 J/m2, respectively. This approach provides a convenient framework to understand the role of the CZM parameters at the interface between the CNT and polymer matrix.

The influence of fiber surface profile and roughness to fiber–matrix interfacial properties

2019 ◽  
Vol 54 (11) ◽  
pp. 1441-1452
Author(s):  
Ichsan Setya Putra ◽  
Bentang Arief Budiman ◽  
Poetro Lebdo Sambegoro ◽  
Sigit Puji Santosa ◽  
Andi Isra Mahyuddin ◽  
...  
Keyword(s):  
Composite Structures ◽  
Cohesive Zone Model ◽  
Surface Profile ◽  
Interfacial Strength ◽  
Fiber Surface ◽  
Interfacial Properties ◽  
Zone Model ◽  
The Matrix ◽  
Fiber Matrix ◽  
New Perspective

This work investigates the influence of fiber surface profile and roughness to fiber–matrix interfacial properties. A series of the push-out test is performed using specimens with different fiber surface profile and roughness. Numerical simulation is then carried out by employing a finite element method to fit the experimental data. The model contains an indenter which pushes in a single fiber from the matrix, while the cohesive zone model is applied to represent the interface resulting in force–displacement curves. Our results suggest that continuous cavities formed in graphite-based fiber may not be beneficial to interfacial properties since it can accelerate a debonding process along with the interface. In contrast, scattered cavities on the fiber surface create strong mechanical locking, which increases the interfacial strength. These results broaden the understanding of the surface profile, which would shed light on a new perspective in designing composite structures.

scholarly journals Ultrasonic Deicing Efficiency Prediction and Validation for a Flat Deicing System

2020 ◽  
Vol 10 (19) ◽  
pp. 6640
Author(s):  
Zhonghua Shi ◽  
Zhenhang Kang ◽  
Qiang Xie ◽  
Yuan Tian ◽  
Yueqing Zhao ◽  
...  
Keyword(s):  
Lead Zirconate Titanate ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Lead Zirconate ◽  
Efficiency Factor ◽  
Zone Model ◽  
Shear Stresses ◽  
Stress Distributions ◽  
Total Energy Density ◽  
Average Shear

An effective deicing system is needed to be designed to conveniently remove ice from the surfaces of structures. In this paper, an ultrasonic deicing system for different configurations was estimated and verified based on finite element simulations. The research focused on deicing efficiency factor (DEF) discussions, prediction, and validations. Firstly, seven different configurations of Lead zirconate titanate (PZT) disk actuators with the same volume but different radius and thickness were adopted to conduct harmonic analysis. The effects of PZT shape on shear stresses and optimal frequencies were obtained. Simultaneously, the average shear stresses at the ice/substrate interface and total energy density needed for deicing were calculated. Then, a coefficient named deicing efficiency factor (DEF) was proposed to estimate deicing efficiency. Based on these results, the optimized configuration and deicing frequency are given. Furthermore, four different icing cases for the optimize configuration were studied to further verify the rationality of DEF. The effects of shear stress distributions on deicing efficiency were also analyzed. At same time, a cohesive zone model (CZM) was introduced to describe interface behavior of the plate and ice layer. Standard-explicit co-simulation was utilized to model the wave propagation and ice layer delamination process. Finally, the deicing experiments were carried out to validate the feasibility and correctness of the deicing system.

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