Effect of Ply Drop in Aerospace Composite Structures

2020 ◽  
Vol 847 ◽  
pp. 46-51
Author(s):  
Prakash Jadhav
Keyword(s):  
Composite Structures ◽  
Mechanical Performance ◽  
Laminated Composite ◽  
Carbon Composite ◽  
Thickness Variation ◽  
Element Analysis ◽  
Short Beam ◽  
Beam Shear ◽  
Carbon Composite Materials ◽  
Point Bend

In most of the aerospace laminated composite structures, thickness variation is achieved by introducing the ply drops at the appropriate locations. Ply drop means the resin rich regions created due to abrupt ending of individual plies within the set of plies. This research is focused on understanding and quantifying the effect of these ply drop regions on the mechanical performance of the aerospace composite structures. This is achieved here by designing the appropriate coupons (with and without ply drops) and analyzing them using finite element analysis. Some typical designs of coupons were manufactured using aerospace grade carbon composite materials, and then tested under four-point bend, cantilever and short beam shear tests to check and validate the effect that was seen in the analysis. It is concluded here that allowable failure strains are different for with and without ply drop cases by a significant amount.

scholarly journals Finite Element Modelling of Frequency-Dependent Dynamic Behaviour of Viscoelastic Composite Structures

2004 ◽  
Vol 13 (1) ◽  
pp. 096369350401300 ◽  
Author(s):  
Evgeny Barkanov ◽  
Andris Chate
Keyword(s):  
Finite Element ◽  
Composite Structures ◽  
Laminated Composite ◽  
Element Analysis ◽  
Viscoelastic Composite ◽  
Fitting Procedure ◽  
Damping Characteristics ◽  
Storage And Loss Moduli ◽  
Free Vibration Frequency ◽  
Viscoelastic Layers

Finite element analysis of sandwich and laminated composite structures with viscoelastic layers is performed. The present implementation gives the possibility to preserve the frequency dependence for the storage and loss moduli of viscoelastic materials exactly. Moreover, the storage and loss moduli in this case are defined directly in the frequency domain by an experimental technique for each material and can be used after curve fitting procedure in the numerical analysis. Damping characteristics of viscoelastic composite structures are evaluated by the energy method, the method of complex eigenvalues, from the resonant peaks of the frequency response function and using the steady state vibrations. Numerical examples are given to demonstrate the validity and application of the approaches developed for the free vibration, frequency and transient response analyses.

scholarly journals The effect of processing on the microstructure of hoop-wound composite cylinders

2020 ◽  
Vol 54 (26) ◽  
pp. 3981-3997 ◽  
Author(s):  
Kaspar Lasn ◽  
Mats Mulelid
Keyword(s):  
Mechanical Performance ◽  
Pressure Vessels ◽  
Void Content ◽  
Cylinder Wall ◽  
Process Innovations ◽  
Short Beam ◽  
Beam Shear ◽  
Composite Microstructure ◽  
The Difference ◽  
Composite Cylinders

Fibre-reinforced polymer composites are increasingly used to make pipes and pressure vessels. The relationship between wet-winding manufacturing, composite microstructure, and the mechanical performance is complex due to many process parameters and material properties involved. Efficient manufacturing aspirations however drive process innovations that include new, radically different tow impregnation methods. In this work, the process–property–performance relationship is experimentally construed for hoop-wound carbon fibre/epoxy composite cylinders. The difference between cylinders produced by a new tow impregnation system and cylinders from the reference impregnation system was investigated. Winding speed and cylinder wall thickness were considered as two additional variables. The results indicate that, within current scope, composite microstructure is relatively insensitive to the winding speed and to final cylinder thickness. Meanwhile, un-optimized changes for tow impregnation affect the void content, the size distribution of voids and the interlaminar failure mode in short beam shear.

Porosity characterization and respective influence on short-beam strength of advanced composite processed by resin transfer molding and compression molding

2020 ◽  
pp. 096739112096845
Author(s):  
Ana Carolina Mendes Quintanilha Silva Santos ◽  
Francisco Maciel Monticeli ◽  
Heitor Ornaghi ◽  
Luis Felipe de Paula Santos ◽  
Maria Odila Hilário Cioffi
Keyword(s):  
Shear Strength ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Optimal Parameter ◽  
Resin Transfer Molding ◽  
Compression Molding ◽  
Viscous Force ◽  
Transfer Molding ◽  
Short Beam ◽  
Beam Shear

This work has been developed for a comparative purpose concerning the processing and respective mechanical performance of CFRP composites processed by resin transfer molding (RTM) and compression molding (CM) techniques. Thermal and viscosimetric tests before processing certified the optimal parameter procedure. Both composites were submitted to short-beam shear tests and through microscopy to determine failure mechanisms. CM specimens presented a decrease of 27% in shear strength caused by the presence of macro porosity that induced crack initiation and connection of different delamination plies, causing the speeding up of crack propagation and jump of the interlaminar layer. The low capillary effect and higher viscous force were responsible for macro porosity, inducing heterogeneous impregnation in CM and to the direction reduce in mechanical behavior. On the other hand, more homogeneous impregnation in RTM specimens was responsible for the absence of macro porosity, ensuring higher values of shear strength and lower void volume fraction.

Development of novel high Tg polyimide-based composites. Part II: Mechanical characterisation

2017 ◽  
Vol 52 (2) ◽  
pp. 261-274 ◽  
Author(s):  
Spyros Tsampas ◽  
Patrik Fernberg ◽  
Roberts Joffe
Keyword(s):  
Elevated Temperature ◽  
Composite System ◽  
Mechanical Performance ◽  
Mechanical Tests ◽  
Basic Material ◽  
Mechanical Characterisation ◽  
Short Beam ◽  
Fibre Treatment ◽  
Beam Shear ◽  
Fibre Matrix

In this study, the mechanical performance assessment of a newly developed carbon fibre-reinforced polyimide composite system T650/NEXIMID® MHT-R is presented. This system was subjected to a series of mechanical tests at ambient and elevated temperature (320℃) to determine basic material properties. Moreover, an additional test was conducted, using a T650/NEXIMID® MHT-R laminate in which the fibre sizing was thermally removed prior to laminate manufacturing, to investigate the effect of fibre treatment on mechanical performance. The experimental results indicated that the T650/NEXIMID® MHT-R composites along with exceptionally high Tg (360–420℃) exhibited competitive mechanical properties to other commercially available polyimide and epoxy-based systems. At elevated temperature, the fibre-dominated properties were not affected whilst the properties defined by matrix and fibre/matrix interface were degraded by approximately 20–30%. Finally, the fibre sizing removal did not affect the tensile and compressive strength, however, the shear strength obtained from short-beam shear test was deteriorated by approximately 15%.

Factors Affecting Tensile Performance of 2D & 3D Angle Interlock Woven Fabric Composite: A Review

2015 ◽  
Vol 1134 ◽  
pp. 147-153 ◽  
Author(s):  
Mohamad Faizul Yahya ◽  
Faris Mohd Zulkifli Nasrun ◽  
Suzaini A. Ghani ◽  
Mohd Rozi Ahmad
Keyword(s):  
Composite Structures ◽  
Mechanical Performance ◽  
Impact Resistance ◽  
Laminated Composite ◽  
Woven Fabric ◽  
Textile Composite ◽  
High Fracture ◽  
Factors Affecting ◽  
Textile Materials ◽  
Delamination Resistance

In recent years, textile composite are widely utilized as structural components in the area of aerospace, civil engineering, protective armour and automotive applications. Textiles structures become increasingly significant for composites application due to strength to weight factor. [1-4]. Various textile materials are extensively used such as fibres, yarns and fabrics. Commonly, textile composite structures are characterized according to the textile preform architecture either it is a conventional 2D laminated structure or 3D textile structural laminated composite [2]. Comparative studies between both types have suggested that 3D textile structure exhibit superior mechanical performance in tensile strength, impact resistance, flexural, delamination resistance, high fracture tolerance [1, 5, 6].

scholarly journals Finite element analysis of bolt shear connection of steel-concrete composite structure

2020 ◽  
Vol 198 ◽  
pp. 01027
Author(s):  
Zhishun Pan
Keyword(s):  
Finite Element ◽  
Composite Structure ◽  
Composite Structures ◽  
Mechanical Performance ◽  
Concrete Strength ◽  
High Strength ◽  
Shear Capacity ◽  
Simulation Software ◽  
Element Analysis ◽  
Shear Connectors

Bolted shear connectors are an important component to ensure that steel-concrete composite structures can work together. High-strength bolt shear connectors can replace traditional stud connectors because of their disassembly, good mechanical performance and fatigue resistance. It applied to steel-concrete composite structure. In order to study the influencing factors of the bearing capacity of high-strength bolted shear connectors, this paper uses ABAQUS finite element simulation software as a research tool to establish a reasonable finite element model to study the influence of bolt strength, bolt diameter and concrete strength on bolted shear connectors. Studies have shown that increasing the diameter, strength, and concrete strength of bolted connections can effectively increase the bolt’s shear capacity.

ON THE EXPERIENCE OF COMPUTED X-RAY TOMOGRAPHY OF REINFORCED THREE-STRINGER PANELS MADE OF POLYMER COMPOSITE MATERIALS

2021 ◽  
pp. 40-49
Author(s):  
A. A. Larin ◽  
M. Yu. Fedotov ◽  
O. N. Budadin ◽  
V. A. Aniskovich ◽  
S. O. Kozel’skaya ◽  
...  
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
High Reliability ◽  
Experimental Studies ◽  
Carbon Composite ◽  
Molding Pressure ◽  
Technical Control ◽  
High Measurement ◽  
Carbon Composite Materials ◽  
Final Inspection

Experimental studies of the possibility of the MCT method for NC three-stringer panels made of PCM by the method of autoclave molding have been carried out. Based on the results of the experimental studies, it was shown that the MCT method makes it possible with a high reliability to identify defects in composite structures at the stage of final inspection (immediately after production), which is especially important for highly loaded and critical structures made of carbon composite materials based on polymer matrices of various types. On the example of testing a three-stringer (reinforced) panel, it is shown that the presented structure as a whole does not have pronounced macrodefects, however, an accumulation of micro-layers is observed in the zone of transition of layers from the sheathing plane to the stringer, which indicates a slight decrease in the molding pressure in this zone. In the studies carried out, these microdefects are not critical, while the results of the tomogram can be used to slightly refine the shape of the tooling in the zone of transition of layers from the skin to the stringer to provide the required molding pressure. Thus, it has been shown that the SRT method is an effective tool for assessing the structure of reinforced composite panels, taking into account different degrees of damage. The high measurement accuracy and resolution of the MCT method allow realizing high reliability and information content of control and ensuring high reliability of PCM structures due to the following factors: • Structures with defects exceeding the maximum permissible ones are not allowed into operation by the technical control department (QCD); • Structures with defects close to the maximum permissible are taken out of service until their properties are restored; • Positioning of defects reduces the labor intensity of repair.

Identification of Damage for a Single and Double Edge Cracks in a Laminated Composite Beam by Using Harmonic Analysis

2015 ◽  
Vol 766-767 ◽  
pp. 14-20
Author(s):  
E.V.V. Ramanamurthy
Keyword(s):  
Harmonic Analysis ◽  
Frequency Response ◽  
Composite Structures ◽  
Damage Identification ◽  
Laminated Composite ◽  
Coupled Modes ◽  
Element Analysis ◽  
Software Application ◽  
Edge Cracks ◽  
Coupled Response

Composite structures are used in many critical engineering applications. In the recent times the research has been increased to identify the damage through the vibrational characteristics of the structure. There have been many theoretical and analytical studies on detection of damage involving analysis of the measured modal parameters, mainly the frequencies. The main objective of this paper is to use coupled response techniques for detecting damages in laminated composite cantilever beams with edge cracks using theoretical harmonic analysis. One method to observe the coupled modes is through the emergence of extra new peaks on a frequency response function plot that can be obtained by using standard vibration testing tools. An attempt has been made to develop a methodology by using coupled response measurements and this will happen to appear only when the structural member contains damage. Therefore, the coupled response can be used to monitor and it can be used to determine the damage existence. The frequency response plots are the only possible method to observe coupled response. The new resonance peaks are correlated to the coupled modes and the appearance of these peaks is the damage identification. The finite element analysis software application package ANSYS 12.0 has been used to obtain the new resonance peaks by using harmonic analysis of undamaged and damaged structures to enable comparisons that throw light on the presence of damages in the structure.

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