A theoretical formulation of the buckling analysis of a composite sandwich structure with multiple holes

2021 ◽  
pp. 109963622110255
Author(s):  
Yongha Kim ◽  
Jungsun Park
Keyword(s):  
Sandwich Structure ◽  
Sandwich Plate ◽  
Homogenization Method ◽  
Buckling Analysis ◽  
Element Analysis ◽  
Theoretical Formulation ◽  
Composite Sandwich ◽  
Aerospace Applications ◽  
Composite Sandwich Structures ◽  
Multiple Holes

This article presents a theoretical formulation presented for conducting a buckling analysis of the composite sandwich plate with multiple holes via the homogenization method. The validity of the theoretical formulation was verified by comparing the results of the finite element analysis and experimental analysis. Finally, the theoretical formulation was used to optimize a composite sandwich plate with multiple holes for the design of an aircraft structure to minimize the mass. The optimization result allows a database to be obtained on the buckling characteristics of composite sandwich structures with multiple holes for applying aerospace applications. We then concluded that the theoretical formulation is well-suited to buckling analysis of a composite sandwich structure with multiple holes for aerospace applications due to their relative simplicity and computational efficiency.

An optimization of composite sandwich structure with passive vibration absorber for vibration suppression

2020 ◽  
pp. 109963622094291
Author(s):  
Yongha Kim ◽  
Jungsun Park
Keyword(s):  
Computational Efficiency ◽  
Sandwich Structure ◽  
Vibration Suppression ◽  
Sandwich Structures ◽  
Ritz Method ◽  
Vibration Absorber ◽  
Composite Sandwich ◽  
Aerospace Applications ◽  
Composite Sandwich Structures ◽  
Approximate Formulation

This article proposes the use of a support as a passive vibration absorber to a composite sandwich structure for vibration suppression of satellite structures. Based on continuous mass distributions, an approximate formulation is presented for conducting vibration (modal, frequency response) analyses of the composite sandwich structure with the support. This formulation is derived by the Ritz method; verified for accuracy and computational efficiency by comparing finite element analyses. Finally, we perform optimization of the composite sandwich structure with passive vibration absorber by the present method. This optimization is conducted to applying satellite structures for maximizing vibration suppression performance in limited mass. The optimization result allows a database to be obtained on the vibration characteristics of composite sandwich structures with passive vibration absorber for applying aerospace applications. Consequently, it is concluded that the approximate formulation is well suited to vibration analyses of composite sandwich structures with passive vibration absorber due to their relative simplicity and computational efficiency.

Effects of core splice joint width on the performance of composite sandwich structures with honeycomb core: An experimental study

2021 ◽  
pp. 109963622110204
Author(s):  
William E Guin ◽  
Alan T Nettles
Keyword(s):  
Sandwich Structure ◽  
Large Scale ◽  
Sandwich Structures ◽  
Composite Sandwich ◽  
Aerospace Applications ◽  
Shear Loads ◽  
Composite Sandwich Structures ◽  
Honeycomb Sandwich ◽  
Joint Width ◽  
Mass Basis

Composite sandwich structures are commonly considered in large-scale aerospace applications due to their performance on a per mass basis. The nature of a large-scale sandwich structure generally necessitates the use of multiple sections of core to fill out the structural form. These core sections must be spliced together to ensure that shear loads are appropriately transmitted throughout the core. Because core installation in a large-scale component is a challenging operation, core splice joint width can be difficult to control in manufacturing. As such, the effects of core splice joint width on sandwich structure performance should be well understood. This study examines the effects of core splice joint width in honeycomb sandwich structures via mechanical testing and post-failure analysis. A threshold core splice joint width is shown to exist with respect to core shear, while the integrity of the facesheet-to-core interface is shown to degrade with increasing core splice joint width.

scholarly journals The energy absorption behavior of novel composite sandwich structures reinforced with trapezoidal latticed webs

2021 ◽  
Vol 60 (1) ◽  
pp. 503-518
Author(s):  
Juan Han ◽  
Lu Zhu ◽  
Hai Fang ◽  
Jian Wang ◽  
Peng Wu
Keyword(s):  
Bearing Capacity ◽  
Energy Absorption ◽  
Sandwich Structure ◽  
Ultimate Load ◽  
Sandwich Structures ◽  
Elastic Displacement ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Composite Sandwich ◽  
Composite Sandwich Structures

Abstract This article proposed an innovative composite sandwich structure reinforced with trapezoidal latticed webs with angles of 45°, 60° and 75°. Four specimens were conducted according to quasi-static compression methods to investigate the compressive behavior of the novel composite structures. The experimental results indicated that the specimen with 45° trapezoidal latticed webs showed the most excellent energy absorption ability, which was about 2.5 times of the structures with vertical latticed webs. Compared to the traditional composite sandwich structure, the elastic displacement and ultimate load-bearing capacity of the specimen with 45° trapezoidal latticed webs were increased by 624.1 and 439.8%, respectively. Numerical analysis of the composite sandwich structures was carried out by using a nonlinear explicit finite element (FE) software ANSYS/LS-DYNA. The influence of the thickness of face sheets, lattice webs and foam density on the elastic ultimate load-bearing capacity, the elastic displacement and initial stiffness was analyzed. This innovative composite bumper device for bridge pier protection against ship collision was simulated to verify its performance. The results showed that the peak impact force of the composite anti-collision device with 45° trapezoidal latticed webs would be reduced by 17.3%, and the time duration will be prolonged by about 31.1%.

Performance of composite sandwich structures under thermal cycling

2019 ◽  
Vol 54 (2) ◽  
pp. 271-283
Author(s):  
Sandesh Rathnavarma Hegde ◽  
Mehdi Hojjati
Keyword(s):  
Crack Formation ◽  
Mechanical Performance ◽  
Crack Density ◽  
Free Edge ◽  
Element Analysis ◽  
Thermally Induced ◽  
Composite Sandwich ◽  
Composite Sandwich Structures ◽  
Number Of Cycles ◽  
Microscopic Inspection

Effect of thermally induced microcracks on mechanical performance of a space grade laminated sandwich panel is investigated. A simple non-contact setup using liquid nitrogen is developed to subject the material to low temperature of −170℃ with cooling rate of 24℃/min. Then the samples are exposed to the elevated temperature of 150℃ inside oven. Microcracks formation and propagation are monitored through microscopic observation of cross-section during the cycling. Flatwise tensile test is performed after a number of cycles. A correlation is made between number of cycles and flatwise mechanical strength after quantifying the microcracks. It is observed that the crack formation gets saturated at about 40 cycles, avoiding the need to conduct more thermal cycles. Microcrack formation both at the free edge and middle of laminate was observed. The crack density at the middle was comparatively less than the ones found on the free edges. Results for non-contact cooling are compared with samples from direct nitrogen contact cooling. Microscopic inspection and flatwise test show differences between contact and non-contact cooled samples. Flatwise tensile strength for non-contact cooled samples shows 15% reduction, while the contact cooled samples have about 30% decrease in bond strength. A 3D finite element analysis is conducted to qualitatively identify the location of stress concentration which can be possible sites of crack formation. Good agreement is observed between the model and experimental results.

Influence of the Honeycomb Geometry on the Sandwich Composite Plate Behavior

2017 ◽  
Vol 1143 ◽  
pp. 139-144 ◽  
Author(s):  
Florentina Rotaru ◽  
Ionel Chirica ◽  
Elena Felicia Beznea
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Sandwich Plate ◽  
Compressive Loading ◽  
Sandwich Composite ◽  
Orthotropic Materials ◽  
Honeycomb Core ◽  
Element Analysis ◽  
Composite Sandwich ◽  
The Impact

In this paper the influence cell honeycomb geometry on the mechanical behaviour of a composite sandwich plate is analyzed. Three cell geometries (circular, hexagonal and square) are static analysed so that to select the best type of honeycomb that will be used in the manufacturing the sandwich plate core. The main aim is to develop approach models of equivalent orthotropic materials to replace the real model of honeycomb core with their properties so that to quickly calculate the sandwich plate made out of composite when is used a finite element analysis code. Geometry and material properties of the honeycomb are delivered by the material provider. Comparative analysis, by using Finite element analysis is performed for all geometries, in the same boundary conditions. Since in the impact loading of the composite sandwich plate the core is mainly loaded to compression, comparative study of the three cell geometries honeycomb was performed for this type of compressive loading. Since the cell is the basic element of the honeycomb core, the calculus is performed for one unit volume of sandwich, concerning also the part of skins.

On Mechanical Properties of Composite Sandwich Structures With Embedded Piezoelectric Fiber Composite Sensors

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Hari P. Konka ◽  
M. A. Wahab ◽  
K. Lian
Keyword(s):  
Composite Structures ◽  
Sandwich Structure ◽  
Sandwich Structures ◽  
Fiber Composite ◽  
Composite Sandwich ◽  
Composite Sandwich Structures ◽  
Analysis Technique ◽  
Short Beam ◽  
Piezoelectric Fiber Composite ◽  
Piezoelectric Fiber

The smart sandwich structures have been widely used in the aerospace, automobile, marine, and civil engineering applications. A typical smart sandwich structure is usually comprised of two stiff face skins separated by a thick core with variety of embedded sensors to monitor the performance of the structures. In this study, the smart composite sandwich structure (CSS) samples are fabricated with glass microballoons syntactic foam core and resin infused glass-fiber face skins (with piezoelectric fiber composite sensors (PFCS) embedded inside the resin infused glass-fiber face skins). One of the main concerns associated with embedding sensors inside composite structures is the structural continuity, compatibility, and interface stress concentrations caused by the significant differences in material property between sensor and host structures. PFCS are highly flexible, easily embeddable, highly compatible with composite structures and their manufacturing processes, which makes them ideal for composite health monitoring applications. In this study, in-plane tensile, tension–tension fatigue, short beam shear, and flexural tests are performed to evaluate the effect on strengths/behavior of the CSS samples due to embedded PFCS. Then carefully planned experiments are conducted to investigate the ability of the embedded PFCS to monitor the stress/strain levels and detect damages in CSS using modal analysis technique. The tensile tests show that both the average ultimate strength and the modulus of elasticity of the tested laminate with or without embedded PFCS are within 7% of each other. The stress–life (S-N) curves obtained from fatigue tests indicates that the fatigue lives and strengths with and without the PFCS are close to each other as well. From short beam and flexural test results, it is observed that embedded PFCS leads to a reduction of 5.4% in the short beam strength and 3.6% in flexural strength. Embedded PFCS’s voltage output response under tension–tension fatigue loading conditions has been recorded simultaneously to study their ability to detect the changes in input loading conditions. A linear relationship has been observed between the changes in the output voltage response of the sensor and changes in the input stress amplitude. This means that by constantly monitoring the output response of the embedded PFCS, one could effectively monitor the magnitude of stress/strain acting on the structure. Experiments are also performed to explore the ability of the embedded PFCS to detect the damages in the structures using modal analysis technique. Results from these experiments show that the PFCS are effective in detecting the initiations of damages like delamination inside these composite sandwich structures through changes in natural frequency modes. Hence embedded PFCS could be an effective method to monitor the health of the composite sandwich structures’ in-service conditions.

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