scholarly journals Analyses of Deformation in Viscoelastic Sandwich Composites Subject to Moisture Diffusion

2008 ◽  
Author(s):  
Nikhil P. Joshi ◽  
Anastasia H. Muliana
Keyword(s):  
Dimensional Stability ◽  
Structural Characteristics ◽  
High Strength ◽  
Moisture Diffusion ◽  
Peel Strength ◽  
Sandwich Composite ◽  
Foam Core ◽  
Sandwich Composites ◽  
Polymer Foam ◽  
Effect Of Moisture

Sandwich composites with polymer foam core are currently used in load-bearing components in buildings and naval structures due to their high strength to weight and stiffness to weight ratios, excellent thermal insulation, and ease of manufacturing. During their service time, sandwich composites are exposed to various external mechanical and hygro-thermal stimuli. It is known that the constituent properties of the sandwich composites are greatly influenced by the temperature and moisture fields. Granville [1] conducted experiments to study the effect of moisture on structural, dimensional stability, weight gain and peel strength of sandwich composites. Morganti et al. [2] analyzed the effect of moisture on the dimensional stability of the sandwich composites and concluded that moisture affects the physical behavior of the composite directly by modifying its structural characteristics such as matrix degradation and microcracks between fiber and matrix etc. However, the effect of moisture on the deformations in the sandwich composite with the viscoelastic foam cores has not yet been studied. The time-dependent response of the sandwich composite (due to the viscoelastic foam core) is aggravated in the moist environment conditions. Thus, it becomes necessary to analyze the effect of moisture on the overall response of the sandwich composites.

Interfacial delamination in glass-fiber/polymer-foam-core sandwich composites using singlemode–multimode–singlemode optical fiber sensors: Identification based on experimental investigation

2017 ◽  
Vol 22 (1) ◽  
pp. 40-54 ◽  
Author(s):  
Nilanjan Mitra ◽  
Alak K. Patra ◽  
Satya P Singh ◽  
Shyamal Mondal ◽  
Prasanta K Datta ◽  
...  
Keyword(s):  
Glass Fiber ◽  
Side Surface ◽  
Cost Effective ◽  
Fiber Optic Sensor ◽  
Sandwich Composite ◽  
Foam Core ◽  
Sandwich Composites ◽  
Strain Sensing ◽  
Polymer Foam ◽  
Interfacial Delamination

Identification of interfacial delamination in the glass fiber/polymer-foam-core sandwich composites is difficult if the delamination does not propagate to the side surface of the specimen. However, these damages may eventually lead to compromising the sandwich composite structural component. A cost-effective novel embedded fiber optic sensor is being proposed in this manuscript, which works on the principle of multimode interference, to perform distributed sensing of interfacial delamination within the sandwich composites while in service. Even though this easy to use methodology has been used to identify interfacial delamination, this methodology can also be used for different other types of interfacial/interlaminar distributed strain sensing of samples under mechanical as well as thermal loads.

Tensile and compressive performances of foam core sandwich composites with various core modifications

2016 ◽  
Vol 19 (1) ◽  
pp. 49-65 ◽  
Author(s):  
Huseyin E Yalkin ◽  
Bulent M Icten ◽  
Tuba Alpyildiz
Keyword(s):  
Sandwich Composite ◽  
Foam Core ◽  
Sandwich Composites ◽  
Time Consumption ◽  
The Core ◽  
Out Of Plane

The objective of this study is to enhance the out-of-plane tensile and compressive performances of foam core sandwich composite via structural core modifications considering the ease of application and time consumption. The performances of single core perforated, single core stitched, divided core perforated, and divided core stitched sandwich composites are compared with each other and reference plain foam core sandwich composites. Results indicate that “perforated and stitched core” sandwich composites have superior strength, and in terms of performance modification, dividing the core is found very efficient for plain (non-perforated and non-stitched) core sandwich composites.

scholarly journals Fabrication and low-velocity impact response of pyramidal lattice stitched foam sandwich composites

2020 ◽  
Vol 27 (1) ◽  
pp. 245-257
Author(s):  
Jiale Jia ◽  
Shi Yan
Keyword(s):  
Numerical Simulation ◽  
Failure Modes ◽  
Absorption Capacity ◽  
Low Velocity Impact ◽  
Sandwich Composite ◽  
Foam Core ◽  
Sandwich Composites ◽  
Low Velocity ◽  
Velocity Impact ◽  
The Impact

AbstractIn this study, the foam sandwich panels were manufactured by integrating top facesheet and bottom facesheet with pyramidal lattice stitched core to overcome the weak interface between the core and skins of the sandwich structures. Low-velocity impact test and numerical simulation were conducted to reveal the failure mechanisms and energy absorption capacity at sandwich composite with foam core, different strut stitched foam core under different impact energy. The experimental results show showed that the strut core can improve the impact resistance of the specimen, and which is closely related to the diameter of the strut core. Compared with foam sandwich structure, pyramidal lattice stitched foam sandwich composites have comparable specific energy absorptions. The failure modes were also analyzed which is: fiber breakage, delamination, foam deformation and strut core breakage. The research presented here confirms that numerical simulation show good agreement with the experiment.

The Effect of Spacer Yarn Arrangement on Compression Behaviors of Novel Flexible Foam-Core Sandwich Composites

2013 ◽  
Vol 821-822 ◽  
pp. 1152-1158 ◽  
Author(s):  
Si Chen ◽  
Hai Ru Long
Keyword(s):  
Strain Curve ◽  
Sandwich Composite ◽  
Foam Core ◽  
Sandwich Composites ◽  
Stress Strain Curve ◽  
Spacer Fabric ◽  
Flexible Foam ◽  
End Use ◽  
Spacer Fabrics ◽  
Hydrophilic Polyurethane

In this study, a kind of novel flexible foam-core sandwich composite was involved. The flexible foam-core sandwich composites were fabricated based on 3D warp-knitted spacer fabrics. The foam-core was filled in the spacer fabric by using a kind of modified hydrophilic polyurethane foam. In order to investigate the effect of spacer yarn inclination angle on the compression behaviors. A compression test was carried out. The compression stress-strain curve was used to analyze the effect of 3D warp-knitted spacer fabric spacer yarn arrangement. According to the experiment results, it indicates that the spacer yarn arrangement could influence the anti-compression capacity of the sandwich composites obviously. Therefore, the spacer yarn arrangement of 3D warp-knitted spacer fabrics can be changed to meet specific end-use requirement for foam-core sandwich composites.

Dynamic impact behavior of syntactic foam core sandwich composites

2019 ◽  
Vol 54 (4) ◽  
pp. 535-547 ◽  
Author(s):  
P Breunig ◽  
V Damodaran ◽  
K Shahapurkar ◽  
S Waddar ◽  
M Doddamani ◽  
...  
Keyword(s):  
Syntactic Foam ◽  
Impact Response ◽  
Sandwich Composite ◽  
Foam Core ◽  
Syntactic Foams ◽  
Sandwich Composites ◽  
Dynamic Impact ◽  
Damage Mechanisms ◽  
The Impact ◽  
Dynamic Impact Loading

Sandwich composites and syntactic foams independently have been used in many engineering applications. However, there has been minimal effort towards taking advantage of the weight saving ability of syntactic foams in the cores of sandwich composites, especially with respect to the impact response of structures. To that end, the goal of this study is to investigate the mechanical response and damage mechanisms associated with syntactic foam core sandwich composites subjected to dynamic impact loading. In particular, this study investigates the influence of varying cenosphere volume fraction in syntactic foam core sandwich composites subjected to varying dynamic impact loading and further elucidates the extent and diversity of corresponding damage mechanisms. The syntactic foam cores are first fabricated using epoxy resin as the matrix and cenospheres as the reinforcement with four cenosphere volume fractions of 0% (pure epoxy), 20%, 40%, and 60%. The sandwich composite panels are then manufactured using the vacuum assisted resin transfer molding process with carbon fiber/vinyl ester facesheets. Dynamic impact tests are performed on the sandwich composite specimens at two energy levels of 80 J and 160 J, upon which the data are post-processed to gain a quantitative understanding of the impact response and damage mechanisms incurred by the specimens. A qualitative understanding is obtained through micro-computed tomography scanning of the impacted specimens. In addition, a finite element model is developed to investigate the causes for different damage mechanisms observed in specimens with different volume fractions.

APEX 417

Alloy Digest ◽  
1958 ◽  
Vol 7 (1) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Dimensional Stability ◽  
High Strength ◽  
Heat Treating ◽  
Casting Alloy ◽  
Excellent Corrosion Resistance ◽  
Magnesium Casting ◽  
Strength And Ductility

Abstract APEX 417 is an aluminum-magnesium casting alloy having high strength and ductility, excellent corrosion resistance and good dimensional stability. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and fatigue. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-61. Producer or source: Apex Smelting Company.

Damage behavior of potting materials in sandwich composites with pinned joints

2015 ◽  
Vol 22 (5) ◽  
Author(s):  
Cesim Atas ◽  
Alper Basmaci
Keyword(s):  
Core Material ◽  
Sandwich Composite ◽  
Composite Panels ◽  
Sandwich Composites ◽  
Resin Infusion ◽  
Damage Behavior ◽  
Mechanical Joints ◽  
The Core ◽  
Bottom Face ◽  
Infusion Technique

AbstractThe damage behavior of the potting materials around a pinhole, being used in the mechanical joints of sandwich composites, is investigated experimentally. The sandwich composite panels used in the tests were manufactured by the vacuum-assisted resin infusion technique. Each of the top and bottom face sheets of the panels consisted of two woven E-glass/epoxy layers. As the core material, PVC foam (AIREX

scholarly journals Effect of Neutron Irradiation on the Mechanical Properties, Swelling and Creep of Austenitic Stainless Steels

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2622
Author(s):  
Malcolm Griffiths
Keyword(s):  
Mechanical Properties ◽  
Stainless Steels ◽  
Dimensional Stability ◽  
Operating Experience ◽  
Austenitic Stainless Steels ◽  
High Strength ◽  
Gas Production ◽  
Rate Theory ◽  
Fast Reactors ◽  
Internal Structures

Austenitic stainless steels are used for core internal structures in sodium-cooled fast reactors (SFRs) and light-water reactors (LWRs) because of their high strength and retained toughness after irradiation (up to 80 dpa in LWRs), unlike ferritic steels that are embrittled at low doses (<1 dpa). For fast reactors, operating temperatures vary from 400 to 550 °C for the internal structures and up to 650 °C for the fuel cladding. The internal structures of the LWRs operate at temperatures between approximately 270 and 320 °C although some parts can be hotter (more than 400 °C) because of localised nuclear heating. The ongoing operability relies on being able to understand and predict how the mechanical properties and dimensional stability change over extended periods of operation. Test reactor irradiations and power reactor operating experience over more than 50 years has resulted in the accumulation of a large amount of data from which one can assess the effects of irradiation on the properties of austenitic stainless steels. The effect of irradiation on the intrinsic mechanical properties (strength, ductility, toughness, etc.) and dimensional stability derived from in- and out-reactor (post-irradiation) measurements and tests will be described and discussed. The main observations will be assessed using radiation damage and gas production models. Rate theory models will be used to show how the microstructural changes during irradiation affect mechanical properties and dimensional stability.

The Applications of Vibratory Stress Relief in High-Strength Aluminum Alloy Thick Plate

2012 ◽  
Vol 430-432 ◽  
pp. 881-885
Author(s):  
Cai Jun Gan ◽  
Kai Liao
Keyword(s):  
Aluminum Alloy ◽  
Residual Stresses ◽  
Dimensional Stability ◽  
Strain Energy ◽  
Thick Plate ◽  
High Strength ◽  
Stress Relief ◽  
High Strength Aluminum Alloy ◽  
Mechanical Stretching ◽  
Stretching Process

The level and distribution of residual stresses have great impact on dimensional stability, while Vibratory Stress Relief (VSR) is an effective technology to relax or homogenize residual stresses. Experimental study on residual stresses distribution, residual strain energy and machining deformation of 7075 high-strength aluminum alloy thick plate under different aging process status shows that VSR can effectively decrease the amplitude and strain energy density, and enhance stability of dislocation structures and phase states in metal microscopic volume, then internal residual stresses are homogenized to enhance components’ anti-deformation capacity. In addition, the capability in maintaining dimensional stability from VSR is better than that from traditional mechanical stretching process

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