scholarly journals Sandwich Structured Composites for Aeronautics: Methods of Manufacturing Affecting Some Mechanical Properties

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Aneta Krzyżak ◽  
Michał Mazur ◽  
Mateusz Gajewski ◽  
Kazimierz Drozd ◽  
Andrzej Komorek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Polymer Composites ◽  
Impact Load ◽  
Sandwich Panels ◽  
Adhesive Layer ◽  
Core Structure ◽  
Road Vehicles ◽  
The Core ◽  
Press Method

Sandwich panels are composites which consist of two thin laminate outer skins and lightweight (e.g., honeycomb) thick core structure. Owing to the core structure, such composites are distinguished by stiffness. Despite the thickness of the core, sandwich composites are light and have a relatively high flexural strength. These composites have a spatial structure, which affects good thermal insulator properties. Sandwich panels are used in aeronautics, road vehicles, ships, and civil engineering. The mechanical properties of these composites are directly dependent on the properties of sandwich components and method of manufacturing. The paper presents some aspects of technology and its influence on mechanical properties of sandwich structure polymer composites. The sandwiches described in the paper were made by three different methods: hand lay-up, press method, and autoclave use. The samples of sandwiches were tested for failure caused by impact load. Sandwiches prepared in the same way were used for structural analysis of adhesive layer between panels and core. The results of research showed that the method of manufacturing, more precisely the pressure while forming sandwich panels, influences some mechanical properties of sandwich structured polymer composites such as flexural strength, impact strength, and compressive strength.

Influence of the Composition of Cement Mortars Modified by Lime or Polymers on the Mechanical Properties and Microstructure of Mortars

2013 ◽  
Vol 592-593 ◽  
pp. 647-650 ◽  
Author(s):  
Małgorzata Lenart
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Reinforced Concrete ◽  
Flexural Strength ◽  
Polyvinyl Alcohol ◽  
Polymer Composites ◽  
Adhesion Strength ◽  
Hardened Cement ◽  
Cement Mortars ◽  
Styrene Butadiene

Cement – polymer composites are nowadays widely used in repair systems not only in case of concrete or reinforced concrete constructions but also in masonry. Polymers addition for example already at 5% m.c. modifies the structure of the cement – polymer composite in a way that many of the mechanical properties such as flexural strength, tensile strength or adhesion to substrates are improved. The paper presents the results of tests such as flexural, compressive or adhesion strength to ceramic substrate of hardened cement mortars with different composition, as well as selected cement mortars modified by two polymers: polyvinyl alcohol and styrene – butadiene polymer dosed at 5 % m.c. Four types of cement mortars modified by lime (component used in historical constructions as well as in contemporary masonry mortars) are also examined for comparison.

Toughening of MDF - OPC Composites

1990 ◽  
Vol 211 ◽  
Author(s):  
C. K. Park ◽  
M. R. Silsbee ◽  
D. M. Roy
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Portland Cement ◽  
Polymer Composites ◽  
Ordinary Portland Cement ◽  
Fine Particles ◽  
Fiber Type ◽  
High Toughness ◽  
Strength And Toughness

AbstractMacro-Defect-Free (MDF) materials are cement-polymer composites exhibiting high flexural strengths and high toughness (for cement based systems). The incorporation of fibers into MDF composites has been found to offer the possibility of increasing both the ultimate flexural strength and toughness of MDF materials prepared using an ordinary portland cement-polyacrylamide matrix.This paper examined the effect of fiber type and fine particles as a packing filler on the resulting mechanical properties. The incorporation of non-traditional materials (for MDF) into the MDF matrix is also discussed.

scholarly journals Simulation of the forming process for curved composite sandwich panels

2019 ◽  
Vol 13 (6) ◽  
pp. 967-980
Author(s):  
S. Chen ◽  
O. P. L. McGregor ◽  
A. Endruweit ◽  
L. T. Harper ◽  
N. A. Warrior
Keyword(s):  
Sandwich Panels ◽  
High Volume ◽  
Core Structure ◽  
Scale Model ◽  
Axial Deformation ◽  
Forming Process ◽  
The Core ◽  
Macro Scale ◽  
Out Of Plane ◽  
Meso Scale

AbstractFor affordable high-volume manufacture of sandwich panels with complex curvature and varying thickness, fabric skins and a core structure are simultaneously press-formed using a set of matched tools. A finite-element-based process simulation was developed, which takes into account shearing of the reinforcement skins, multi-axial deformation of the core structure, and friction at the interfaces. Meso-scale sandwich models, based on measured properties of the honeycomb cell walls, indicate that panels deform primarily in bending if out-of-plane movement of the core is unconstrained, while local through-thickness crushing of the core is more important in the presence of stronger constraints. As computational costs for meso-scale models are high, a complementary macro-scale model was developed for simulation of larger components. This is based on experimentally determined homogenised properties of the honeycomb core. The macro-scale model was employed to analyse forming of a generic component. Simulations predicted the poor localised conformity of the sandwich to the tool, as observed on a physical component. It was also predicted accurately that fibre shear angles in the skins are below the critical angle for onset of fabric wrinkling.

Shear mechanical properties of the core structure of biomimetic fully integrated honeycomb plates

2018 ◽  
Vol 22 (4) ◽  
pp. 1184-1198 ◽  
Author(s):  
Wanyong Tuo ◽  
Jinxiang Chen ◽  
Mengye Xu ◽  
Zhijie Zhang ◽  
Zhensheng Guo
Keyword(s):  
Mechanical Properties ◽  
Failure Mode ◽  
Shear Failure ◽  
Core Structure ◽  
Resin Matrix ◽  
Joint Interface ◽  
Shear Direction ◽  
Material Interface ◽  
Fully Integrated ◽  
The Core

In the present study, the shear failure mode and mechanical properties of the core structure of biomimetic fully integrated honeycomb plates with sealing edges were investigated experimentally and through the finite element method. The findings are as follows: (1) the failure mode of the sealing edges and honeycomb walls perpendicular to the shear direction is mainly debonding between the fiber and matrix, whereas fiber breakage, debonding between the fiber and matrix and exfoliation of the resin matrix occur in the sealing edges parallel to the shear direction. Meanwhile, the reasonableness and feasibility of the double shear testing apparatus designed in this study were verified, thus confirming the results of research are reliable and valid. (2) Shear failure of the core structure of fully integrated honeycomb plates is mainly fiber debonding appearing in the middle surface of the core structure, which is a failure of the material interface. Stripping failure in the joint interface of the core layer and upper and lower plates does not occur, which indicates that the biological structure possesses excellent integral mechanical properties. (3) The sealing edges parallel to the shear direction and the honeycomb walls that are oriented 30 degrees to the shear direction are the first to fail, followed by the sealing edges and honeycomb walls perpendicular to the shear direction, which is consistent with the microscopic failure phenomenon observed in both directions. To prevent failure at the material interface, the fully integrated honeycomb plates manufactured in this experiment require further improvements. Thus, countermeasures are proposed, such as pre-treating the fiber surface. These findings will specify future research directions to perfect fully integrated honeycomb plates and improve the shear mechanical properties of core structures.

scholarly journals EFFECT OF HYBRID FIBER ON THE MECHANICAL PROPERTIES OF RECYCLED AGGREGATE CONCRETE

2018 ◽  
Vol 80 (5) ◽  
Author(s):  
Sallehan Ismail ◽  
Mahyuddin Ramli
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Mechanical Strength ◽  
Impact Load ◽  
Load Resistance ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Normal Concrete ◽  
Aggregate Concrete

This study investigates the effect of inclusion of polyolefin and polypropylene fibers at various volume fractions in single and hybrid forms on the mechanical properties of recycled aggregate concrete (RAC) mix that consists of treated coarse recycled concrete aggregate (RCA). Testing parameters, such as compressive strength, flexural strength, static modulus of elasticity, and impact load resistance, are utilized to evaluate the mechanical strength of specimens. The various properties of the modified RAC are also analyzed and compared with those of normal concrete and unmodified RAC specimens. Findings indicate that the mechanical strength properties of RAC mixture using treated RCA were significantly enhanced by adding fibers. The overall optimized mechanical strength results could be obtained in RAC mixtures with fiber in hybrid form, where their compressive strength at long-term curing age, can be significantly improved by 7% upto 11% higher than normal concrete. In addition, RAC mix with hybrid fibers produced the highest flexural strength and impact load resistance by an increase of 5% and 175%, respectively as compared with the control concrete.  

scholarly journals Experimental Investigation on Mechanical Properties of A/GFRP, B/GFRP and AB/GFRP Polymer Composites

2022 ◽  
Vol 58 (4) ◽  
pp. 28-36
Author(s):  
Velmurugan Natarajan ◽  
Ravi Samraj ◽  
Jayabalakrishnan Duraivelu ◽  
Prabhu Paulraj
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Flexural Strength ◽  
Glass Fiber ◽  
Polymer Composites ◽  
Fiber Reinforced ◽  
Gfrp Composites ◽  
Glass Fiber Reinforced ◽  
Structural Applications ◽  
Polyester Composites

This study aims to reveal the consequence of thickness reinforcement on Fiber Laminates (Polyester Resin, Glass Fiber, Aluminum, and Bentonite) and to see if it can enhance the mechanical properties and resistance of laminates. Glass fiber reinforced polymer composites have recently been used in automotive, aerospace, and structural applications where they will be safe for the application s unique shape. Hand layup was used to fabricate three different combinations, including Aluminium /Glass fiber reinforced polyester composites (A/GFRP), Bentonite/Glass fiber reinforced polyester composites (B/GFRP), and Aluminium&Bentonie/Glass fiber reinforced polyester composites (AB/GFRP). Results revealed that AB/GFRP had better tensile strength, flexural strength, and hardness than GFRP and A/GFRP. Under normal atmospheric conditions and after exposure to boiling water, hybrid Aluminium&Bentonite and glass fiber-reinforced nanocomposites have improved mechanical properties than other hybrid composites. After exposure to temperature, the flexural strength, tensile strength and stiffness of AB/GFRP Composites are 40 % higher than A/GFRP and 17.44% higher than B/GFRP Composites.

scholarly journals Preparation of Polymer Composites using Natural Fiber and their Physico-Mechanical Properties

1970 ◽  
Vol 45 (2) ◽  
pp. 117-122 ◽  
Author(s):  
Husna P Nur ◽  
M Akram Hossain ◽  
Shahin Sultana ◽  
M Mamun Mollah
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Flexural Strength ◽  
Water Absorption ◽  
Polymer Composites ◽  
Natural Fiber ◽  
Banana Fiber ◽  
Elongation At Break ◽  
Reinforcing Material ◽  
Ldpe Composites

Use of natural fiber as reinforcing material is the latest invention of polymer science in order to get higher strength with lower weight composite materials having several applications. In this present investigation banana fiber, a natural fiber, is used as the reinforcing material. Low density polyethylene (LDPE)-banana fiber reinforced composites were prepared using both untreated and bleached (treated) banana fiber and LDPE with 7.5, 15, 22.5 and 30% weight content of fibers by using compression molding technique. Physico-mechanical properties (e.g. tensile strength, flexural strength, elongation at break, Young's modulus) of different types of prepared composites were characterized. From this study it is observed that all these values have augmented up to a definite percentage. The tensile strengths and flexural strengths of the composites increased up to 22.5% fiber addition then started to decrease gradually. Young moduli of the composites increased with the increase of fiber addition. Water absorption also increased with the weight of the fiber. Whereas elongation at break decreased with increasing fiber loading. Mechanical properties of bleached banana fiber-LDPE composites were slightly higher than the untreated banana fiber-LDPE composites. Compared to virgin molded LDPE both tensile and flexural strengths and Young moduli of these LDPE-banana fiber composites were significantly higher. All the variable properties like tensile strength, flexural strength, and water absorption capacity showed a very significant role in these polymer composites. Keywords: Banana fiber; LDPE; Composite; Tensile strength; Flexural strength DOI: 10.3329/bjsir.v45i2.5708Bangladesh J. Sci. Ind. Res. 45(2), 117-122, 2010

Flexural Properties of Kenaf Sandwich Panel

2012 ◽  
Vol 567 ◽  
pp. 216-219
Author(s):  
Zahurin Halim ◽  
Siti Khadijah Abdul Rahman
Keyword(s):  
Mechanical Properties ◽  
Steel Sheet ◽  
Sandwich Panel ◽  
Core Structure ◽  
Main Element ◽  
Flexural Properties ◽  
Skin Thickness ◽  
The Core ◽  
Galvanised Steel

This study concerns on effect of varying skin thickness to flexural properties of sandwich panel. The main element of the core structure is kenaf and the skin used in this study is galvanised steel sheet. Skin thickness being used in this research is 1.0 mm and 1.2 mm. In this study, comparing sandwich of skin thickness 1.0 mm and 1.2 mm, result shows that 1.0 mm skin is sufficient as mechanical properties of sandwich decreases and density of sandwich increases as skin thickens.

scholarly journals Effect of Hybridization on the Mechanical Properties of Chopped Strand Mat/Pineapple Leaf Fibre Reinforced Polyester Composites

2018 ◽  
Vol 153 ◽  
pp. 01006 ◽  
Author(s):  
Suhas Yeshwant Nayak ◽  
Srinivas Shenoy Heckadka ◽  
Nishank Minil Amin ◽  
Ramakrishna Vikas Sadanand ◽  
Linto George Thomas
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Flexural Strength ◽  
Polymer Composites ◽  
Matrix Cracking ◽  
Reinforced Composites ◽  
Pull Out ◽  
The Matrix ◽  
Chopped Strand Mat ◽  
Hybrid Laminate

Hybridization of synthetic and natural fibres as reinforcement makes the polymer composites environmental friendly and sustainable when compared to synthetic fibres based polymer composites. In this study chopped strand mat/pineapple leaf fibres were hybridized. Four laminates with six layers each, with different stack sequence (GGGGGG, GPPPPG, PGGGGP and PPPPPP) were fabricated using hand layup technique while maintaining a fibre to matrix ratio of 30:70 by weight with polyester resin as matrix. Mechanical properties such as tensile and flexural strength were determined and morphology of fractured specimens was studied. Maximum tensile strength of 180 MPa was obtained for the laminate with six layers of chopped strand mat followed by hybrid laminate with four layers of chopped strand mat at the centre (120 MPa). Tensile strength of hybrid laminate with four layers of pineapple leaf fibres at the centre was in third position at 86 MPa. Least tensile strength of 65 MPa was obtained for the laminate with six layers of pineapple leaf fibres. Similar trend was observed in case of flexural behaviour of the laminates with maximum flexural strength of 255 MPa and minimum flexural strength 107 MPa. Scanning electron microscopy of the fractured specimen reinforced with chopped strand mat only, indicated, fibre pull out, matrix cracking and lack of matrix adhesion to fibres. In case of hybrid composite (GPPPPG and PGGGGP) delamination was observed to be prominent due to improper wetting of the pineapple leaf fibres with the matrix. More significant delamination led to lesser strength in case of pineapple fibres reinforced composites even though the fibre pull out was relatively less.

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