Ram Load Simulation of Wing Skin-Spar Joints: New Rate-dependent Cohesive Model

2006 ◽  
Author(s):  
Monty A. Moshier
Keyword(s):  
Cohesive Model ◽  
Rate Dependent ◽  
Wing Skin ◽  
Load Simulation

scholarly journals Calibration of a Cohesive Model for Fracture in Low Cross-Linked Epoxy Resins

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1321 ◽  
Author(s):  
Dery Torres ◽  
Shu Guo ◽  
Maria-Pilar Villar ◽  
Daniel Araujo ◽  
Rafael Estevez
Keyword(s):  
Epoxy Resin ◽  
Epoxy Resins ◽  
Glassy Polymer ◽  
Failure Process ◽  
Shear Bands ◽  
Glassy Polymers ◽  
Constitutive Law ◽  
Cohesive Model ◽  
Rate Dependent ◽  
Structural Applications

Polymer-based composites are becoming widely used for structural applications, in particular in the aeronautic industry. The present investigation focuses on the mechanical integrity of an epoxy resin of which possible damage results in limitation or early stages of dramatic failure. Therefore, a coupled experimental and numerical investigation of failure in an epoxy resin thermoset is carried out that opens the route to an overall micromechanical analysis of thermoset-based composites. In the present case, failure is preceded by noticeable plasticity in the form of shear bands similar to observations in ductile glassy polymers. Thus, an elastic-visco-plastic constitutive law initially devoted to glassy polymer is adopted that captures the rate- dependent yield stress followed by softening and progressive hardening at continued deformation. A general rate-dependent cohesive model is used to describe the failure process. The parameters involved in the description are carefully identified and used in a finite element calculation to predict the material’s toughness for different configurations. Furthermore, the present work allows investigation of nucleation and crack growth in such resins. In particular, a minimum toughness can be derived from the model which is difficult to evaluate experimentally and allows accounting for the notch effect on the onset of failure. This is thought to help in designing polymer-based composites.

Effects of grain boundary heterogeneities on creep fracture studied by rate-dependent cohesive model

2012 ◽  
Vol 93 ◽  
pp. 48-64 ◽  
Author(s):  
Chi-Hua Yu ◽  
Chang-Wei Huang ◽  
Chuin-Shan Chen ◽  
Yanfei Gao ◽  
Chun-Hway Hsueh
Keyword(s):  
Grain Boundary ◽  
Cohesive Model ◽  
Creep Fracture ◽  
Rate Dependent

Analysis of a rate-dependent cohesive model for dynamic crack propagation

2002 ◽  
Vol 70 (5) ◽  
pp. 685-704 ◽  
Author(s):  
Dhirendra V. Kubair ◽  
Philippe H. Geubelle ◽  
Yonggang Y. Huang
Keyword(s):  
Crack Propagation ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack ◽  
Cohesive Model ◽  
Rate Dependent

scholarly journals Numerical Study on the Dynamic Fracture Energy of Concrete Based on a Rate-Dependent Cohesive Model

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7421
Author(s):  
Penglin Zhang ◽  
Zhijun Wu ◽  
Yang Liu ◽  
Zhaofei Chu
Keyword(s):  
Strain Rate ◽  
Fracture Energy ◽  
Dynamic Fracture ◽  
Loading Rate ◽  
Numerical Study ◽  
Damage Zone ◽  
Concrete Fracture ◽  
Obvious Effect ◽  
Cohesive Model ◽  
Rate Dependent

As an important parameter for concrete, fracture energy is difficult to accurately measure in high loading rate tests due to the limitations of experimental devices and methods. Therefore, the utilization of numerical methods to study the dynamic fracture energy of concrete is a simple and promising choice. This paper presents a numerical investigation on the influence of loading rate on concrete fracture energy and cracking behaviors. A novel rate-dependent cohesive model, which was programmed as a user subroutine in the commercial explicit finite element solver LS-DYNA, is first proposed. After conducting mesh sensitivity analysis, the proposed model is calibrated against representative experimental data. Then, the underlying mechanisms of the increase in fracture energy due to a high strain rate are determined. The results illustrate that the higher fracture energy during dynamic tension loading is caused by the wider region of the damage zone and the increase in real fracture energy. As the loading rate increases, the wider region of the damage zone plays a leading role in increasing fracture energy. In addition, as the strain rate increases, the number of microcracks whose fracture mode is mixed mode increases, which has an obvious effect on the change in real fracture energy.

A loading rate dependent cohesive model for concrete fracture

2012 ◽  
Vol 82 ◽  
pp. 195-208 ◽  
Author(s):  
A.L. Rosa ◽  
R.C. Yu ◽  
G. Ruiz ◽  
L. Saucedo ◽  
J.L.A.O. Sousa
Keyword(s):  
Loading Rate ◽  
Concrete Fracture ◽  
Cohesive Model ◽  
Rate Dependent

Mesoscopic simulation of the dynamic tensile behaviour of concrete based on a rate-dependent cohesive model

2016 ◽  
Vol 95 ◽  
pp. 165-175 ◽  
Author(s):  
Wei Zhou ◽  
Longwen Tang ◽  
Xinghong Liu ◽  
Gang Ma ◽  
Mingxiang Chen
Keyword(s):  
Tensile Behaviour ◽  
Cohesive Model ◽  
Mesoscopic Simulation ◽  
Rate Dependent

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

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