scholarly journals Analysis of contact interaction of polymer honeycomb core and CFRP base layers in sandwich-core constructions

2021 ◽  
Vol 20 (1) ◽  
pp. 87-96
Author(s):  
S. A. Pavlova
Keyword(s):  
Contact Interaction ◽  
Composite Structures ◽  
High Strength ◽  
Complex Stress ◽  
Shear Stresses ◽  
Honeycomb Core ◽  
Shear Tests ◽  
Reinforced Plastics ◽  
Four Point Bending ◽  
Sandwich Core

The article considers the challenge of studying the mechanical properties of composite sandwich constructions at the interface between the base layers and the lightweight core. The results of strength tests are presented for specimens of sandwich-core panels with coats made of high-strength carbon fiber-reinforced plastics (CFRP) and polymer honeycomb core considering various loading conditions. It is noted that a discrepancy in the values of shear stresses occurs in four-point bending and shear tests due to the complex stress-strain state of the specimens during bending. In order to interpret the experimental data, numerical analysis of the area of contact interaction between the coats and the filler of the sandwich-core composite structures is carried out. It is noted that in the presence of significant normal stresses in the adhesive coat the base layers separate from the core during shear tests and there is underestimation of the values of shear stresses by about 20%. Recommendations for the assignment of ultimate shear stresses for the use in practical design of sandwich-core composite constructions are put forward.

Mechanical and Fracture Mechanical Properties of Matrix-Reinforced Carbon Fiber Composites with Carbon Nanotubes

2019 ◽  
Vol 809 ◽  
pp. 615-619 ◽  
Author(s):  
Gerhard Sinn ◽  
Gerald Singer ◽  
Leo Jocher ◽  
Miriam M. Unterlass ◽  
Harald Rennhofer ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
High Strength ◽  
Negative Influence ◽  
Carbon Fiber Composites ◽  
Bending Tests ◽  
Reinforced Plastics ◽  
Aerospace Applications ◽  
Four Point Bending ◽  
Low Weight ◽  
Strength And Stiffness

Carbon fiber reinforced Plastics are materials with high strength and stiffness at low weight compared to metals. These properties make the materials ideal candidate for structures in aerospace applications, where they are often used under bending conditions. Due to the strongly anisotropic composition the CFRP typically fail in compression by fiber buckling. In order to improve this weakness, nanotube and nanofiber reinforced matrix was used to build CFRP. Four-point bending tests showed that stiffness and strength could be improved by the fillers, whereas negative influence was found on fracture energy.

The Effect of Fiber Winding Angles on the Bending Strength of Fiber-Reinforced Plastic Rods

2007 ◽  
Vol 345-346 ◽  
pp. 661-664
Author(s):  
Hoy Yul Park ◽  
Moon Kyong Na ◽  
Myeong Sang Ahn ◽  
Seog Young Yoon ◽  
Seong Soo Park
Keyword(s):  
Bending Strength ◽  
High Strength ◽  
Shear Stresses ◽  
Fiber Reinforced ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastics ◽  
Reinforced Plastic ◽  
Bending Load ◽  
The Difference ◽  
Fiber Winding

Fiber-reinforced plastics consist of fibers of high strength and modulus embedded in, or bonded to a matrix with distinct interfaces between them. Because fiber configuration plays a key role in determining mechanical strength of fiber-reinforced plastic rods, especially bending strength of fiber-reinforced plastic rods was measured and simulated numerically in variation with winding angles. Also, stress distribution in fiber-reinforced plastic rods was simulated numerically under the condition of constant bending load to fiber-reinforced plastic rods. The measured bending strength of fiber-reinforced plastic rods in variation with winding angles was different from that of simulated. The difference between measured and simulated results was due to the effect of shear stresses on the strength of fiber-reinforced plastic rods.

FEM Analysis and Experimental Study for Bond Strength of High-Strength Coating by Wedged Load Test Method

2010 ◽  
Vol 152-153 ◽  
pp. 1058-1061
Author(s):  
Zhou Wei ◽  
Xiao Xia Zhang
Keyword(s):  
Bond Strength ◽  
Adhesion Strength ◽  
Fem Analysis ◽  
High Strength ◽  
Pressure Head ◽  
Optical Microscope ◽  
Complex Stress ◽  
Complex Stress State ◽  
Load Test ◽  
Test Method

A wedged load test method is used to evaluate the adhesion strength of high-strength coatings, which have been processed with various sintering parameters. In this test, for stress concentration at cut tip, cracks are always induced and expanded rapidly cross the interface between coating and substrate. Macro-fracture and SEM image of coating interface of high-strength coating are characterized using optical microscope and scanning electron microscopy (SEM), respectively. In order to evaluate the bonding properties between coating and substrate effectively, corresponding finite element (FE) analysis has been conducted to evaluate the adhesion strength of high-strength coating. And stress distributions cross the interface of high-strength coating are obtained. The stress analysis can help to evaluate the bond strength of high-strength coating. Because of small specimen and contact relationship between wedged pressure head and wedged cuts, complex stress state is affected by many factors resulting from interface, and also by the thickness of coating.

Stresses in Ultrasonically Assisted Turning

2006 ◽  
Vol 5-6 ◽  
pp. 351-358 ◽  
Author(s):  
N. Ahmed ◽  
A.V. Mitrofanov ◽  
Vladimir I. Babitsky ◽  
Vadim V. Silberschmidt
Keyword(s):  
Ultrasonic Vibration ◽  
Vibration Frequency ◽  
Cutting Forces ◽  
Plastic Material ◽  
Process Zone ◽  
Three Dimensional ◽  
Rate Sensitivity ◽  
High Strength ◽  
Material Model ◽  
Shear Stresses

Ultrasonically assisted turning (UAT) is a novel material-processing technology, where high frequency vibration (frequency f ≈ 20kHz, amplitude a ≈15μm) is superimposed on the movement of the cutting tool. Advantages of UAT have been demonstrated for a broad spectrum of applications. Compared to conventional turning (CT), this technique allows significant improvements in processing intractable materials, such as high-strength aerospace alloys, composites and ceramics. Superimposed ultrasonic vibration yields a noticeable decrease in cutting forces, as well as a superior surface finish. A vibro-impact interaction between the tool and workpiece in UAT in the process of continuous chip formation leads to a dynamically changing stress distribution in the process zone as compared to the quasistatic one in CT. The paper presents a three-dimensional, fully thermomechanically coupled computational model of UAT incorporating a non-linear elasto-plastic material model with strain-rate sensitivity and contact interaction with friction at the chip–tool interface. 3D stress distributions in the cutting region are analysed for a representative cycle of ultrasonic vibration. The dependence of various process parameters, such as shear stresses and cutting forces on vibration frequency and amplitude is also studied.

Design of crack arrestors for ultra high grade gas transmission pipelines: simulation of crack initiation, propagation and arrest

2011 ◽  
Vol 2 (2) ◽  
pp. 307-319
Author(s):  
F. Van den Abeele ◽  
M. Di Biagio ◽  
L. Amlung
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Large Scale ◽  
Large Diameter ◽  
Pipe Material ◽  
High Grade ◽  
Gas Pipelines ◽  
Ductile Crack ◽  
Reinforced Plastics ◽  
Four Point Bending

One of the major challenges in the design of ultra high grade (X100) gas pipelines is the identification of areliable crack propagation strategy. Recent research results have shown that the newly developed highstrength and large diameter gas pipelines, when operated at severe conditions, may not be able to arrest arunning ductile crack through pipe material properties. Hence, the use of crack arrestors is required in thedesign of safe and reliable pipeline systems.A conventional crack arrestor can be a high toughness pipe insert, or a local joint with higher wall thickness.According to experimental results of full-scale burst tests, composite crack arrestors are one of the mostpromising technologies. Such crack arrestors are made of fibre reinforced plastics which provide the pipewith an additional hoop constraint. In this paper, numerical tools to simulate crack initiation, propagationand arrest in composite crack arrestors are introduced.First, the in-use behaviour of composite crack arrestors is evaluated by means of large scale tensile testsand four point bending experiments. The ability of different stress based orthotropic failure measures topredict the onset of material degradation is compared. Then, computational fracture mechanics is applied tosimulate ductile crack propagation in high pressure gas pipelines, and the corresponding crack growth inthe composite arrestor. The combination of numerical simulation and experimental research allows derivingdesign guidelines for composite crack arrestors.

Buckling Analysis of Carbon Fiber Reinforced Plastics Cylinders under Axial Compression

2013 ◽  
Vol 395-396 ◽  
pp. 76-79
Author(s):  
Da Huang ◽  
Cheng Hong Duan
Keyword(s):  
Carbon Fiber ◽  
Axial Compression ◽  
Composite Structures ◽  
Fiber Reinforced ◽  
Element Analysis ◽  
Carbon Fiber Reinforced Plastics ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics ◽  
Carbon Fiber Reinforced ◽  
The Stability

In this paper, the stability of carbon fiber reinforced plastics (CFRP) cylinders under axial compression was studied by the finite element analysis method. According to the Riks method, compressive capacity of the composite structures was investigated by nonlinear analysis, in which the eigen buckling modes were considered in the form of initial defects. And the post-buckling performances of different structures were also compared.

scholarly journals Numerical Simulation on Micro-damage Detection In CFRP Composites Based on Nonlinear Ultrasonic Guided Waves

2021 ◽  
Keyword(s):  
Damage Detection ◽  
Composite Structures ◽  
Guided Waves ◽  
Second Harmonic ◽  
Wave Mode ◽  
Guided Wave ◽  
Reinforced Plastics ◽  
Matrix Cracks ◽  
Nonlinear Ultrasonic ◽  
Contact Acoustic Nonlinearity

Abstract. Micro-damages such as pores, closed delamination/debonding and fiber/matrix cracks in carbon fiber reinforced plastics (CFRP) are vital factors towards the performance of composite structures, which could collapse if defects are not detected in advance. Nonlinear ultrasonic technologies, especially ones involving guided waves, have drawn increasing attention for their better sensitivity to early damages than linear acoustic ones. The combination of nonlinear acoustics and guided waves technique can promisingly provide considerable accuracy and efficiency for damage assessment and materials characterization. Herein, numerical simulations in terms of finite element method are conducted to investigate the feasibility of micro-damage detection in multi-layered CFRP plates using the second harmonic generation (SHG) of asymmetric Lamb guided wave mode. Contact acoustic nonlinearity (CAN) is introduced into the constitutive model of micro-damages in composites, which leads to the distinct SHG compared with material nonlinearity. The results suggest that the generated second order harmonics due to CAN could be received and adopted for early damage evaluation without matching the phase of the primary waves.

scholarly journals Performance analysis of the bump beams made of High Strength Steel and Carbon Fiber reinforce plastics

2018 ◽  
Vol 207 ◽  
pp. 03006
Author(s):  
Yi Yao ◽  
Quan Yuan ◽  
Sihuan Fu
Keyword(s):  
Carbon Fiber ◽  
Automobile Industry ◽  
High Strength Steel ◽  
Lightweight Design ◽  
High Strength ◽  
Research Directions ◽  
Deformation And Failure ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics ◽  
Fiber Reinforce

Lightweight and safe are the key research directions of the automobile industry. Bump beam is an important part of the car safety protection and it’s lightweight design has drawn much attention. In this paper, the static strength and the low-speed impact performances of two types of bump beam with the same structure, which made of carbon fiber reinforced plastics (CFRP) and high strength steel (HSS), were investigated. Under the condition of static press, frontal and 40% offset impact, part structural stiffness, component crush intrusion, energy absorption were comparison analyzed. In order to guide the product design, the deformation and failure of CFRP beams with five different laminate structures were simulated under frontal and 40% offset impact. The results indicate that, with the same structure, the properties of CFRP bump beam are generally superior to HSS product, more conducive to lightweight and the optimum design of the laminate is [0° / 60° / 120°]

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