Investigation on Interlaminar Mechanical Properties of Hybrid CFRP/VGCF Laminates

2009 ◽  
Vol 79-82 ◽  
pp. 1759-1762
Author(s):  
Yuan Li ◽  
Naoki Hori ◽  
Masahiro Arai ◽  
Hisao Fukunaga ◽  
Ning Hu
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Fracture Toughness ◽  
Finite Element ◽  
Tensile Strength ◽  
Crack Growth ◽  
Double Cantilever Beam ◽  
Cohesive Elements ◽  
Cfrp Laminates ◽  
Delamination Propagation

In order to improve the interlaminar mechanical properties of CFRP laminate, hybrid CFRP/VGCF laminates have been fabricated by newly-developed powder method. The critical load at crack growth Pc and fracture toughness GIC have been found to be increased with VGCF interlayer through double cantilever beam (DCB) tests. Fracture surfaces of DCB specimens have also been observed to interpret this improvement mechanism. Moreover, numerical simulations using finite element method (FEM) with cohesive elements have been carried out to analyze the delamination propagation. The numerically obtained interlaminar tensile strength of hybrid CFRP/VGCF laminates has also been verified to be higher than that of base CFRP laminates.

Determination of Fracture Toughness From Small Punch Test Using Inverse Finite Element Method for In-Service Equipment

2017 ◽  
Author(s):  
Kaishu Guan ◽  
Tong Xu ◽  
Linling Guo ◽  
Mingxue Fu ◽  
Huadong Zhu
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Fracture Toughness ◽  
Finite Element ◽  
Displacement Curve ◽  
Small Punch Test ◽  
Small Punch ◽  
Punch Test ◽  
Inverse Finite Element Method ◽  
Load Displacement

Fracture toughness is the most important reference index in safety assessment, life prediction of nuclear reactor, pressure equipment, and risk assessment of pressure equipment containing defects. Conventional mechanical test specimens require a large amount of materials and cannot be carried out on in-service pressure equipment. The specimen of small punch test (SPT) is much smaller than conventional one, and can be sampled from the surface of pressure equipment. Repair is not acquired after sampling. Many mechanical properties parameters of the material can be determined from the load-displacement curve of test. SPT makes up the deficiencies of conventional mechanical properties test. In this paper, an innovative approach, inverse finite element method (IFEM), is proposed to deal with the load-displacement curve. The procedure of IFEM can be divided into 3 steps. Step 1, a database containing a variety set of material parameters and their corresponding load-displacement curve will be built using FEM. Step 2; a set of matched material parameter of test load-displacement curve will be selected from the database by artificial neutral network (ANN). Step 3, a numerical simulation of fracture toughness test will be performed and fracture toughness Jic will be determined from the result of simulation. Compared with empirical correlation method, IFEM is much more theoretical and needs not to perform a large number of small punch tests and conventional mechanical tests to create a correlation equation between the mechanical property and load-displacement curve. So IFEM is more efficiency and accurate.

Mechanical properties of a hierarchical honeycomb with sandwich walls

2016 ◽  
Vol 230 (16) ◽  
pp. 2765-2775 ◽  
Author(s):  
Ting Yi
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Fracture Toughness ◽  
Finite Element ◽  
Relative Density ◽  
Young’S Modulus ◽  
Elastic Limit ◽  
Young's Modulus ◽  
Peak Strength ◽  
Element Method

The in-plane compressive collapse and fracture toughness of a hierarchical hexagonal honeycomb with sandwich walls consisting of corrugated cores are studied by using finite element method. Its near-optimal configuration is identified by maximizing its elastic limit, which is determined by three competing failure modes including plastic yielding of the larger struts, or elastic wrinkling of the face sheets of the larger struts, or elastic buckling of the smaller struts. The overall mechanical properties of the optimal hierarchical honeycomb, including the Young’s modulus, elastic limit, peak strength, and fracture toughness are obtained from finite element method simulation and compared with analytical predictions, and the discrepancy between the two is explained. The optimal hierarchical honeycomb is found to be superior to its equivalent mass first-order honeycomb in all the mechanical properties listed above when the relative density is low (about 10%). Moreover, the Young’s modulus, elastic limit and peak strength under plastic failure mode, and the fracture toughness of this optimal hierarchical honeycomb are shown to depend linearly upon its relative density. This paper provides additional insights into hierarchical cellular materials.

Displacement-controlled crack growth in double cantilever beam specimen: A comparative study of different models

2016 ◽  
Vol 231 (15) ◽  
pp. 2835-2847 ◽  
Author(s):  
Ali Abbaszadeh Bidokhti ◽  
Amir Reza Shahani ◽  
Mohammad Reza Amini Fasakhodi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Closed Form ◽  
Crack Growth ◽  
Elastic Foundation ◽  
Cantilever Beam ◽  
Double Cantilever Beam ◽  
Beam Specimen ◽  
Extended Finite Element ◽  
Double Cantilever Beam Specimen

This paper presents, discusses, and compares different techniques to model fracture initiation and static crack growth in double cantilever beam specimen under displacement-controlled loading. Energy release rate, critical displacement for the onset of crack growth, and critical load were determined by analytical solution, standard, and extended finite element method. The crack growth was also examined, and the advantages of each method were described as well. In addition, the compliance technique was used in the analytical method. In this regard, the crack growth relations were formulated based on four models including simple Euler–Bernoulli model, Euler–Bernoulli on the elastic foundation, simple Timoshenko beam, and the beam on the elastic foundation considering shear effects. Closed-form relations were extracted for the fracture parameters. Afterward, the Abaqus software was utilized to simulate the crack growth by the standard finite element method. Since the extended finite element has the ability to model the discontinuities inside the elements, the problem was also simulated by this method. Cohesive fracture of double cantilever beam specimen was performed using a closed-form solution and using a finite element model. Results of different modeling techniques were determined and compared.

KAISER ALUMINUM ALLOY 7050

Alloy Digest ◽  
2000 ◽  
Vol 49 (1) ◽  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
Aluminum Alloy ◽  
Heat Treating ◽  
High Fracture Toughness ◽  
High Fracture ◽  
Kaiser Aluminum ◽  
Structural Parts ◽  
Very High

Abstract Kaiser Aluminum Alloy 7050 has very high mechanical properties including tensile strength, high fracture toughness, and a high resistance to exfoliation and stress-corrosion cracking. The alloy is typically used in aircraft structural parts. This datasheet provides information on composition, physical properties, hardness, tensile properties, and shear strength as well as fracture toughness and fatigue. It also includes information on forming, heat treating, machining, and joining. Filing Code: AL-366. Producer or source: Tennalum, A Division of Kaiser Aluminum.

Finite Element Modeling of Microcrack Growth in Cortical Bone

2011 ◽  
Vol 78 (4) ◽  
Author(s):  
Susan Mischinski ◽  
Ani Ural
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Elastic Modulus ◽  
Crack Growth ◽  
Line Strength ◽  
Crack Deflection ◽  
Cement Line ◽  
Fracture Properties ◽  
Cement Lines ◽  
Microcrack Growth

Bone is similar to fiber-reinforced composite materials made up of distinct phases such as osteons (fiber), interstitial bone (matrix), and cement lines (matrix-fiber interface). Microstructural features including osteons and cement lines are considered to play an important role in determining the crack growth behavior in cortical bone. The aim of this study is to elucidate possible mechanisms that affect crack penetration into osteons or deflection into cement lines using fracture mechanics-based finite element modeling. Cohesive finite element simulations were performed on two-dimensional models of a single osteon surrounded by a cement line interface and interstitial bone to determine whether the crack propagated into osteons or deflected into cement lines. The simulations investigated the effect of (i) crack orientation with respect to the loading, (ii) fracture toughness and strength of the cement line, (iii) crack length, and (iv) elastic modulus and fracture properties of the osteon with respect to the interstitial bone. The results of the finite element simulations showed that low cement line strength facilitated crack deflection irrespective of the fracture toughness of the cement line. However, low cement line fracture toughness did not guarantee crack deflection if the cement line had high strength. Long cracks required lower cement line strength and fracture toughness to be deflected into cement lines compared with short cracks. The orientation of the crack affected the crack growth trajectory. Changing the fracture properties of the osteon influenced the crack propagation path whereas varying the elastic modulus of the osteon had almost no effect on crack trajectory. The findings of this study present a computational mechanics approach for evaluating microscale fracture mechanisms in bone and provide additional insight into the role of bone microstructure in controlling the microcrack growth trajectory.

Double Cantilever Beam Measurement and Finite Element Analysis of Cryogenic Mode I Interlaminar Fracture Toughness of Glass-Cloth/Epoxy Laminates

2000 ◽  
Vol 123 (2) ◽  
pp. 191-197 ◽  
Author(s):  
Y. Shindo ◽  
K. Horiguchi ◽  
R. Wang ◽  
H. Kudo
Keyword(s):  
Fracture Toughness ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Cantilever Beam ◽  
Double Cantilever Beam ◽  
Mode I ◽  
Interlaminar Fracture Toughness ◽  
Element Analysis ◽  
Interlaminar Fracture ◽  
Delamination Crack

An experimental and analytical investigation in cryogenic Mode I interlaminar fracture behavior and toughness of SL-E woven glass-epoxy laminates was conducted. Double cantilever beam (DCB) tests were performed at room temperature (R.T.), liquid nitrogen temperature (77 K), and liquid helium temperature (4 K) to evaluate the effect of temperature and geometrical variations on the interlaminar fracture toughness. The fracture surfaces were examined by scanning electron microscopy to verify the fracture mechanisms. A finite element model was used to perform the delamination crack analysis. Critical load levels and the geometric and material properties of the test specimens were input data for the analysis which evaluated the Mode I energy release rate at the onset of delamination crack propagation. The results of the finite element analysis are utilized to supplement the experimental data.

Revealing Mechanical Strength of Nanopores Using Atomic Finite Element Techniques

2018 ◽  
Vol 934 ◽  
pp. 24-29
Author(s):  
Prapasiri Pongprayoon ◽  
Attaphon Chaimanatsakun
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Fluid Flow ◽  
Mechanical Strength ◽  
Impact Force ◽  
Pore Surface ◽  
Vertical Rectangle ◽  
The Impact ◽  
Graphene Nanopore

Graphene nanopore has been widely employed in nanofilter or nanopore devices due to its outstanding properties. The understanding of its mechanical properties at nanoscale is crucial for device improvement. In this work, the mechanical properties of graphene nanopore is thus investigated using atomistic finite element method (AFEM). Four graphene models with different pore shapes (circular (CR), horizontal rectangle (RH), and vertical rectangle (RV)) in sub-nm size which could be successfully fabricated experimentally have been studied here. The force normal to a pore surface is applied to mimic the impact force due to a fluid flow. Increasing pore size results in the reduction in its strength. Comparing among different pore shapes with comparable sizes, the order of pore strength is CR>RH>RV>SQ. In addition, we observe that the direction of pore alignment and geometries of pore edge also play a key role in mechanical strength of nanopores.

Collapse of Tubes Under Combined Bending and Axial Compression Loads

2018 ◽  
Author(s):  
Shan Jin ◽  
Shuai Yuan ◽  
Yong Bai
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Axial Compression ◽  
Local Buckling ◽  
Practical Application ◽  
Buckling Modes ◽  
Combined Loads ◽  
Bending Loads ◽  
Good Agreement

In practical application, pipelines will inevitably experience bending and compression during manufacture, transportation and offshore installation. The mechanical behavior of tubes under combined axial compression and bending loads is investigated using experiments and finite element method in this paper. Tubes with D/t ratios in the range of 40 and 97 are adopted in the experiments. Then, the ultimate loads and the local buckling modes of tubes are studied. The commercial software ABAQUS is used to build FE models to simulate the load-shortening responses of tubes under combined loads. The results acquired from the ABAQUS simulation are compared with the ones from verification bending experiment, which are in good agreement with each other. The models in this paper are feasible to analyze the mechanical properties of tubes under combined axial compression and bending loads. The related results may be of interest to the manufacture engineers.

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