Finite element analyses on three-point low-cyclic bending fatigue of 3-D braided composite materials at microstructure level

2014 ◽  
Vol 84 ◽  
pp. 41-53 ◽  
Author(s):  
Liwei Wu ◽  
Fa Zhang ◽  
Baozhong Sun ◽  
Bohong Gu
Keyword(s):  
Finite Element ◽  
Composite Materials ◽  
Finite Element Analyses ◽  
Bending Fatigue ◽  
Cyclic Bending ◽  
Braided Composite

Finite element analyses on bending fatigue of three-dimesional five-directional braided composite T-beam with mixed unit-cell model

2017 ◽  
Vol 52 (9) ◽  
pp. 1139-1154 ◽  
Author(s):  
Yiwei Ouyang ◽  
Baozhong Sun ◽  
Bohong Gu
Keyword(s):  
Finite Element ◽  
Cell Model ◽  
Unit Cell ◽  
Finite Element Analyses ◽  
Unit Cell Model ◽  
Joint Region ◽  
Bending Fatigue ◽  
Braided Composite ◽  
T Beam ◽  
Interior Cell

This paper reports the bending fatigue behavior of three-dimensional five-directional braided T-shaped composite from finite element analyses and experimental characterizations. The braided composite microstructure was divided into five types of unit cell models, that is, interior cell, surface cell, corner cell, interior cell in joint region, and corner cell in joint region. A user-defined material subroutine was developed to characterize the unit cells properties, damage accumulation, and failure criterion of the T-beam under different stress levels. The stiffness degradation curves and bending displacement curves were obtained from the finite element analysis to show the three stages of fatigue developments, that is, matrix cracks, interface debonding, and fiber breaking. The stress and strain concentration areas were found in the middle of the flange and the web of the T-beam composites. The high strength reinforced fibers are recommended to add in the middle of the flange and the web for improving the bending fatigue resistance. And also, we hope the mixed unit-cell model could be extended to the other braided composite structures under quasi-static or cyclic loadings.

Behaviors of Composite Circular Struts in Space Environment: Analyses and Experiments

2004 ◽  
Vol 261-263 ◽  
pp. 797-802
Author(s):  
Chul Kim ◽  
Jong Heun Lee ◽  
J.H. Kim ◽  
Hoon Sang Choi
Keyword(s):  
Genetic Algorithm ◽  
Finite Element ◽  
Composite Materials ◽  
Optimal Design ◽  
Thermal Analyses ◽  
Space Environment ◽  
Stacking Sequence ◽  
Finite Element Analyses ◽  
Axial Deformation ◽  
Generic Algorithms

The optimal stacking sequence and wall thickness of the composite strut tubes were determined to minimize thermal strains during orbital operation using generic algorithms and finite element analyses. From the results of previous thermal analyses of composite struts with various stacking sequences, the axial deformation is a matter of prime importance. For this reason, the optimization focuses to minimize the axial strains. The balanced and symmetric stacking sequences are used to minimize the radial and the twisting deformations. The genetic algorithm is known to be very effective for the discrete optimization such as stacking sequences of composite materials. As a result, the thermal deformations of the strut with an optimal stacking sequence are almost zero. The optimal strut tube consists of 6 plies and the weight of a composite strut is 22.4% that of aluminum strut. Finite element analyses showed that the optimal design of composite strut tubes withstood combined launch loads without buckling and failure. To validate the analyses, four composite struts were fabricated and their thermal strains were measured under the temperature increase of 100°C. The thermal and vibration experiments showed excellent correlations with analytical results.

Experimental Study and Finite Element Simulation of Bending Fretting Fatigue for Tempered 42CrMo Steel

2016 ◽  
Vol 725 ◽  
pp. 394-398
Author(s):  
Jun Ding ◽  
Yi Lin Zhu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Steel Plate ◽  
Element Model ◽  
Fretting Fatigue ◽  
Cyclic Softening ◽  
Bending Fatigue ◽  
Cyclic Bending ◽  
42Crmo Steel ◽  
Bending Loads

In this paper, experiments of the plain bending fatigue for cyclic softening material tempered 42CrMo steel plate and the bending fretting fatigue for tempered 42CrMo steel plate against 52100 bearing steel cylinder are conducted. The difference of the bending fretting fatigue and the plain bending fatigue for tempered 42CrMo steel is analyzed, and the effect of cyclic bending loads with the same normal load on the fatigue lives is discussed. Besides, finite element simulations of the bending fretting fatigue process for tempered 42CrMo steel by ABAQUS are carried out. In this simulation, an advanced cyclic elasto-plastic constitutive model is implemented in to ABAQUS as a user material subroutine (UMAT) in order to consider the influence of ratchetting and cyclic softening feature. And a simplified equivalent two-dimensional plane strain finite element model with an equivalent normal force obtained from the three-dimensional finite element model is adopted. From the numerical simulation, the influence of cyclic bending loads on the bending fretting fatigue for tempered 42CrMo steel is discussed, and then the bending fretting fatigue lives are estimated by employing Smith–Watson–Topper critical plane criteria. Comparison with the corresponding experiments shows that the estimated results are in good agreement with the experimental results.

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