scholarly journals A Macro-Meso Correlation Model for Numerical Simulation of CFRP Tensile Notched Strength

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Fang Chen ◽  
Weixing Yao ◽  
Wen Jiang
Keyword(s):  
Composite Laminates ◽  
Ultimate Load ◽  
Fracture Morphology ◽  
Volume Element ◽  
External Loading ◽  
Geometrical Parameters ◽  
Correlation Model ◽  
Damage Initiation ◽  
Simulation Results ◽  
Notched Strength

In this paper, the tensile mechanical behavior of Carbon Fiber Reinforced Plates (CFRP) with central open-holes was studied by experimental and simulation ways. A correlation model was built by macromechanical analysis and mesodamage analysis to form a progressive analysis architecture. Composite laminates were disassembled into two kinds: Representative Volume Element (RVE), which were 3D intralayer orthotropic, and the 2D interlayer cohesive element. The macromechanical analysis built connections between external loading cases and RVE stress distribution filed. The mesodamage analysis aimed to determine multimode damage initiation and evolution inside RVE. By comparing simulation results with experimental data, the prediction accuracy on failure mode, ultimate load, and fracture morphology were good enough to show the effectiveness and rationality of this new model. In addition, this model’s applicability to different material and geometrical parameters was also verified by simulating the experiment results in the literature.

scholarly journals Geometrical Effects on Ultrasonic Al Bump Direct Bonding for Microsystem Integration: Simulation and Experiments

Micromachines ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 750
Author(s):  
Jun-Hao Lee ◽  
Pin-Kuan Li ◽  
Hai-Wen Hung ◽  
Wallace Chuang ◽  
Eckart Schellkes ◽  
...  
Keyword(s):  
Shear Strength ◽  
Joint Strength ◽  
Maximum Stress ◽  
Geometrical Parameters ◽  
Experimental Demonstration ◽  
Joint Shear Strength ◽  
Element Analysis ◽  
Ultrasonic Bonding ◽  
Simulation Results ◽  
Geometrical Effects

This study employed finite element analysis to simulate ultrasonic metal bump direct bonding. The stress distribution on bonding interfaces in metal bump arrays made of Al, Cu, and Ni/Pd/Au was simulated by adjusting geometrical parameters of the bumps, including the shape, size, and height; the bonding was performed with ultrasonic vibration with a frequency of 35 kHz under a force of 200 N, temperature of 200 °C, and duration of 5 s. The simulation results revealed that the maximum stress of square bumps was greater than that of round bumps. The maximum stress of little square bumps was at least 15% greater than those of little round bumps and big round bumps. An experimental demonstration was performed in which bumps were created on Si chips through Al sputtering and lithography processes. Subtractive lithography etching was the only effective process for the bonding of bumps, and Ar plasma treatment magnified the joint strength. The actual joint shear strength was positively proportional to the simulated maximum stress. Specifically, the shear strength reached 44.6 MPa in the case of ultrasonic bonding for the little Al square bumps.

Damage Characterization in Glass/Epoxy Composite Laminates under Normal and Oblique Planes of Cyclic Indentation Loading with AE Monitoring

2021 ◽  
Vol 79 (1) ◽  
pp. 61-77
Author(s):  
A Jayababu ◽  
V Arumugam ◽  
B Rajesh ◽  
C Suresh Kumar
Keyword(s):  
Compressive Strength ◽  
Acoustic Emission ◽  
Cyclic Loading ◽  
Composite Laminates ◽  
Epoxy Composite ◽  
Damage Resistance ◽  
Damage Initiation ◽  
Residual Compressive Strength ◽  
Cyclic Indentation ◽  
Indentation Damage

This work focuses on the experimental investigation of indentation damage resistance in different stacking sequences of glass/epoxy composite laminates under cyclic loading on normal (0°) and oblique (20°) planes. The stacking sequence, such as unidirectional [0]12, angle ply [±45]6S, and cross ply [0/90]6S, were subjected to cyclic indentation loading and monitoring by acoustic emission testing (AE). The laminates were loaded at the center using a hemispherical steel indenter with a 12.7 mm diameter. The cyclic indentation loading was performed at displacements from 0.5 to 3 mm with an increment of 0.5 mm in each cycle. Subsequently, the residual compressive strength of the post-indented laminates was estimated by testing them under in-plane loading, once again with AE monitoring. Mechanical responses such as peak load, absorbed energy, stiffness, residual dent, and damage area were used for the quantification of the indentation-induced damage. The normalized AE cumulative counts, AE energy, and Felicity ratio were used for monitoring the damage initiation and propagation. Moreover, the discrete wavelet analysis of acoustic emission signals and fast Fourier transform enabled the calculation of the peak frequency content of each damage mechanism. The results showed that the cross-ply laminates had superior indentation damage resistance over angle ply and unidirectional (UD) laminates under normal and oblique planes of cyclic loading. However, the conclusion from the results was that UD laminates showed a better reduction in residual compressive strength than the other laminate configurations.

Study on Micro-Fracture Chaotic Evolution under External Loading Rock

2013 ◽  
Vol 813 ◽  
pp. 355-358 ◽  
Author(s):  
Ting Ting Wang ◽  
Wan Chun Zhao ◽  
Yuan Hong Liu ◽  
Li Yang ◽  
Hong Yu Gao
Keyword(s):  
Finite Element ◽  
Chaos Theory ◽  
Formation Process ◽  
Theoretical Calculations ◽  
Growth Behavior ◽  
External Loading ◽  
Software Simulation ◽  
Finite Element Software ◽  
Fracture Formation ◽  
Simulation Results

In order to accurately describe the growth behavior of the micro-fracture under the action of the rock external load, this paper proposes the use of chaos theory to describe the fracture formation process, explains the chaotic characteristics of the fracture from the perspective of the growth of micro-fracture, the number of growth and fracture formation morphology, respectively. Selecting the practical block of an oilfield, the theoretical calculation and finite element software simulation results show that, theoretical calculations are accurate and reliable.

Designing Composites for Graceful Failure

2020 ◽  
Author(s):  
Amany Micheal ◽  
Yehia Bahei-El-Din ◽  
Mahmoud E. Abd El-Latief
Keyword(s):  
Mechanical Properties ◽  
Energy Dissipation ◽  
Composite Laminates ◽  
Ultimate Load ◽  
Low Cost ◽  
Cost Effective ◽  
Carbon Composite ◽  
Three Point Bending ◽  
Glass Carbon ◽  
Effective Product

Abstract When inevitable, failure in composite laminates is preferred to occur gracefully to avoid loss of property and possibly life. While the inherent inhomogeneity leads to slow dissipation of damage-related energy, overall failure is fiber-dominated and occurs in a rather brittle manner. Multidirectional plies usually give a more ductile response. Additionally, stiffness and strength as well as cost are important factors to consider in designing composite laminates. It is hence desirable to optimize for high mechanical properties and low cost while keeping graceful failure. Designing composite laminates with hybrid systems and layups, which permit gradual damage energy dissipation, are two ways proposed in this work to optimize for mechanical properties while avoiding catastrophic failure. In the hybrid system design, combining the less expensive glass reinforced plies with carbon reinforced plies offers a cost-effective product, marginal mechanical properties change and ductile profile upon failure. Hybrid glass/carbon composite laminates subjected to three-point bending showed strain to failure which is double that measured for carbon composite specimens, without affecting the ultimate load. Energy dissipation mechanisms were also created by building laminates which were intentionally made discontinuous by introducing cuts in the fibers of the interior plies. This created a longer path for damage before cutting through the next ply resulting in double failure strain with marginal reduction in load. The effect of fiber discontinuity in terms of spacing and distribution are among the factors considered.

scholarly journals Flexural Testing of Composite Laminates for Drilling Trial Assessment

2000 ◽  
Vol 9 (4) ◽  
pp. 096369350000900
Author(s):  
I.R. Farrow ◽  
J. Lee ◽  
C.D. Kong
Keyword(s):  
Composite Laminates ◽  
Composite Laminate ◽  
Static Tension ◽  
Hole Quality ◽  
Flexural Testing ◽  
Open Hole ◽  
Drilling Parameter ◽  
Flexural Tests ◽  
Notched Strength ◽  
Composite Samples

This work presents a study of flexural testing as a convenient method for ranking drilling trials of composite materials. The work includes an experimental study of drilling parameter effects on composite laminate hole quality as measured by static tension, compression and flexural open hole tests. Flexural testing and results processed in terms of the outermost 0° layer provides a consistent ranking of holes drilled with different process parameters despite only subtle changes in static notched strength for the thick composite samples tested. Specific observations from flexural tests are consistent with current drilling practices in terms of best process parameter settings and the method shows sufficient sensitivity to distinguish between the effects of drill-entry and drill-exit damage and subtle changes in lay-up.

Strength prediction of woven composite rings using progressive damage modeling

2020 ◽  
Vol 29 (6) ◽  
pp. 851-873
Author(s):  
H Khayyam Rayeni ◽  
AH Mazaheri ◽  
F Taheri-Behrooz
Keyword(s):  
Representative Volume Element ◽  
Stiffness Matrix ◽  
Volume Element ◽  
Progressive Damage ◽  
Equivalent Stiffness ◽  
Woven Composite ◽  
Damage Initiation ◽  
Plain Weave ◽  
Representative Volume ◽  
Composite Pipe

The ultimate failure of the woven composite pipes has been investigated using progressive damage modeling. The composite pipe specimens were made of (E) glass plain weave fabrics according to the ASTM D2290 standard. The hoop strength of these specimens has been obtained from the tensile tests. The damage initiation and propagation of composite pipe have been predicted by a numerical multi-scale method. For this purpose, the damage of the yarns and resin of the plain weave laminate was investigated by modeling a representative volume element. Then, the macroscopic stresses and strains of the representative volume element were calculated to obtain the equivalent stiffness matrix using suitable boundary conditions. Then, the mechanical properties of the laminate and material properties degradation coefficients were derived by this equivalent stiffness matrix. Hashin and Von Mises failure criteria were utilized in USDLFD subroutine to predict the damage initiation of the yarn and resin in the representative volume element, respectively. The sudden degradation method has been used to investigate the damage propagation in these constituents. Then, the woven composite ring was modeled in ABAQUS software and its ultimate strength was predicted by UMAT subroutine using obtained degradation coefficients of the representative volume element from the previous step. Finally, the numerical results were compared with the experimental data which show good agreement between the results.

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