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.

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.

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%.

On the Use of a Woven Mat to Control the Crack Path in Composite Sandwich Specimens With Foam Core

2007 ◽  
Author(s):  
Christian Lundsgaard-Larsen ◽  
Christian Berggreen ◽  
Leif A. Carlsson
Keyword(s):  
Fracture Toughness ◽  
Sandwich Structure ◽  
Large Scale ◽  
Sandwich Structures ◽  
Crack Tip ◽  
Complex Stress ◽  
Propagation Path ◽  
Composite Sandwich ◽  
The Face ◽  
Bridging Fibers

In the last couple of decades the use of sandwich structures has increased tremendously in applications where low weight is of importance e.g. ship structures, where sandwich panels are often built from fiber reinforced faces and foam cores. An important damage type in sandwich structures is separation of face and core (debonding). Debonds can arise as a result of defects from production when an area between face and core has not been primed sufficiently resulting in a lack of adhesion. In use, impact loading, e.g. due to collision with objects, can result in formation of a debond crack, followed by growth due to continued loading. With debonds present the structure might fail under loads significantly lower than those for an intact sandwich structure [1, 2]. A debond crack in a foam cored sandwich can propagate self similarly or kink away from the interface into either the face or core. Whether or not kinking occurs is governed by the stress state at the crack tip, e.g. described by the mode-mixity of the complex stress intensity factor and the properties of the face, core and adhesive [3]. The criticality of an existing crack can be highly dependent on the crack propagation path, since the fracture toughness of the face, core and interface are often very different. As the crack propagates in the interface or laminate the fibers in the face laminate can form a bridging zone behind the crack tip. This can increase the fracture toughness significantly since the bridging fibers provide closing tractions between the separated crack surfaces [4, 5]. The outline of a crack propagating under large scale bridging in a sandwich structure can be seen in Figure 1.

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.

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.

Sandwich Structures With Smart Composite Face Skin

2011 ◽  
Author(s):  
Hari Prasad Konka ◽  
M. A. Wahab ◽  
Kun Lian
Keyword(s):  
Glass Fiber ◽  
Composite Structures ◽  
Sandwich Structure ◽  
Sandwich Structures ◽  
Fiber Composite ◽  
Fatigue Tests ◽  
Smart Composite ◽  
Composite Sandwich ◽  
Composite Sandwich Structures ◽  
Composite Face

Sandwich structures are one of the very important classes of composite structures that have been studied quite extensively in the past few years. The concepts of sandwich structures have been widely used in the aerospace, automobile, marine, and civil engineering applications; because it is suitable and amenable to the development of light-weight structures with high in-plane and flexural stiffness. A typical sandwich structure is usually comprised of two stiff face skins, which are separated by a thick, lightweight, and compliant core. The primary function of the face skin sheets in a sandwich structure is to provide required bending and in-plane shear stiffness and to carry edge-wise bending and in-plane loads. The composite face skins are usually made from resin impregnated glass fiber or a laminate of unidirectional fibers (prepregs), graphite prepregs, aluminum alloys or many other refractory metal alloys. In this study, smart composite face skins comprise of the composite layers with embedded Piezoelectric Fiber Composite Sensors (PFCS). The functions of PFCS as an embedded sensor inside the composite sandwich structure are threefold: (i) to detect all loading conditions acting on to the structure, (ii) to detect the damages while in-service under dynamic loads, and finally, (iii) to monitor the pre-existing damages in the structure so that their severity can be ascertained to avoid eventual catastrophic or premature failures. The PFCS are generally an ideal choice for this type of sandwich structures applications, as they are highly flexible, easily embeddable; their high compatibility to the composite manufacturing techniques; and more importantly, they produce significantly less interfacial stresses when embedded inside the composite structures. This research is focused on examining the effects on the structural integrity of the composite sandwich structure (with glass micro-balloons syntactic foam core and resin infused glass fiber face skins) with PFCS embedded inside face skin. In-plane tensile, and tension-tension fatigue tests are performed to evaluate the strengths/behavior of the composites containing embedded PFCS. The tensile tests showed that both the average ultimate strength and the modulus of elasticity of the tested laminate with or without embedded PFCS are within 7%. 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. Then carefully planned experiments are conducted to investigate the ability of the embedded PFCS to monitor the stress/strain levels and detect damages in composite sandwich structure. Experiments were performed to explore the ability of the embedded PFCS (MFC and PFC) to detect the damages in the structures using modal analysis method. Results from these experiments shows 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 a smart composite face skin can be an effective method to monitor the health of the composite sandwich structures’ in-service conditions.

Dynamic cushioning energy absorption of paper composite sandwich structures with corrugation and honeycomb cores under drop impact

2021 ◽  
pp. 109963622110288
Author(s):  
Meijuan Ji ◽  
Yanfeng Guo ◽  
Xuxiang Han ◽  
Yungang Fu ◽  
Jianfen Kang ◽  
...  
Keyword(s):  
Energy Absorption ◽  
Composite Structure ◽  
Sandwich Structure ◽  
Sandwich Structures ◽  
Drop Impact ◽  
Composite Sandwich ◽  
Composite Sandwich Structures ◽  
Honeycomb Cores ◽  
Paper Honeycomb ◽  
Better Than

The paper composite sandwich structure with corrugation and honeycomb cores has been widely used in civil and national defense industries, and the cushioning energy absorption characteristic is a key indicator to evaluate the performance of this composite structure. Therefore, this paper is focus on the influences of honeycomb thickness on the shock acceleration response and deformation characteristics to analyze cushioning energy absorption performance of the composite structure by various experimental tests. The experimental result shows that, the paper corrugation layer firstly comes into crushed, and then the paper honeycomb layer is crushed. Additionally, the large honeycomb thickness may cause the secondary collapse of paper honeycomb layer. Under the same impact energy or impact mass, the cushioning energy absorption of the single-sided composite sandwich structure is better than that of the double-sided structure with the same honeycomb thickness. However, the impact resistance of the double-sided composite structure is better than that of the single-sided structure. For the paper composite sandwich structures with the honeycomb thicknesses 10, 15, 20 and 25 mm, the increase of honeycomb thickness would decrease the cushioning energy absorption of the whole structure under the drop impact with low energy. However, under the drop impact with high energy, the influence of honeycomb thickness on cushioning energy absorption is contrary. For the paper composite sandwich structure, the specific energy absorption, unit volume energy absorption, and stroke efficiency for the honeycomb thicknesses 10, 15, 20 and 25 mm are higher than those for the honeycomb thickness 70 mm. Therefore, the low honeycomb thickness is more advantageous for the cushioning energy absorption of paper composite sandwich structure.

Sign in / Sign up

Export Citation Format

Share Document