Improving four-point bending performance of marine composite sandwich beams by core modification

2020 ◽  
Vol 54 (8) ◽  
pp. 1049-1066
Author(s):  
F Balıkoğlu ◽  
N Arslan ◽  
TK Demircioğlu ◽  
O İnal ◽  
M İren ◽  
...  
Keyword(s):  
Bending Strength ◽  
Mechanical Performance ◽  
Composite Beams ◽  
Bending Stiffness ◽  
Bending Test ◽  
Sandwich Composite ◽  
Foam Core ◽  
Sandwich Beams ◽  
Bending Performance ◽  
Four Point Bending

The aim of this study was to improve four-point bending performance of foam core sandwich composite beams by applying various core machining configurations. Sandwich composites have been manufactured using perforated and grooved foam cores by vacuum-assisted resin transfer moulding method with vinyl-ester resin system. The influence of grooves and perforations on the mechanical performance of marine sandwich composite beams was investigated under four-point bending test considering the weight gain. Bending strength and effective bending stiffness increased up to 34% and 61%, respectively, in comparison to a control beam without core modification. Analytical equations were utilised for calculating the mid-span deflection, equivalent bending stiffness and ultimate bending strength of the sandwich beams. Finite element analysis was also performed to analyse the flexural response of the specimens taking into account the combined effect of orthotropic linear elasticity of the face sheet and the non-linear behaviour of the foam core.

Bending Fatigue Behaviour of Laminated Sandwich Beams

2012 ◽  
Vol 445 ◽  
pp. 548-553 ◽  
Author(s):  
Onur Coskun ◽  
Halit S. Türkmen
Keyword(s):  
Free Vibration ◽  
Vibration Frequency ◽  
Mechanical Performance ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Bending Stiffness ◽  
Bending Test ◽  
Sandwich Beams ◽  
Bending Fatigue ◽  
Free Vibration Frequency

In this study, the bending fatigue behaviour of laminated sandwich beams, which are made of carbon/epoxy face sheets and aramid honeycomb core, has been investigated experimentally. The wet hand lay-up technique is used and curing is processed on the heated vacuum table at an elevated temperature to manufacture the sandwich beams. The experimental set-up for bending fatigue test provides a cantilever in one end and a cyclic load at the free end with constant displacement amplitude at room temperature. The load applied to the beam is measured using a load cell during the bending test. Different displacement amplitudes are performed. Mechanical properties, bending stiffness and free vibration frequency of the sandwich beam are investigated. The bending test of the beams and vibration identification test using a vibration analyzer, a hammer and an accelerometer are performed to measure the bending stiffness and determination of free vibration frequency of the clamped sandwich beams before starting and after completion of the fatigue tests. The bending stiffness and free vibration frequencies before and after the fatigue tests are compared to understand the effect of repeated loadings on the mechanical performance of the laminated sandwich beams.

Research on Damage and Bending Properties of AZ31 Magnesium Alloy

2012 ◽  
Vol 184-185 ◽  
pp. 1163-1166
Author(s):  
Xi An Xie ◽  
Gao Feng Quan
Keyword(s):  
Magnesium Alloy ◽  
Applied Load ◽  
Bending Strength ◽  
Az31 Magnesium Alloy ◽  
Bending Test ◽  
Bending Properties ◽  
Four Point Bending ◽  
Heat Treated ◽  
Four Point Bending Test ◽  
Initial Cracks

Through the four-point bending test of lath-shaped heat treated AZ31 magnesium alloy, the bending properties and damage characteristics were explored. The results show that the optimal bending strength of the magnesium alloy were 355.1MPa and 259.2MPa for extruded and cast samples, respectively, after corresponding heat treatment with 350°C, 90min and 400°C, 30min. The initial cracks both occurred at the loading point after applied load exceeded the yield limit of AZ31 magnesium alloy. Surface bump, cracks and other damage morphology accompanied by a large number of twinning organizations were found on the surface of the samples.

Experimental investigations on the sandwich composite beams and panels with elastomeric foam core

2017 ◽  
Vol 21 (3) ◽  
pp. 865-894 ◽  
Author(s):  
AR Nazari ◽  
H Hosseini-Toudeshky ◽  
MZ Kabir
Keyword(s):  
Carrying Capacity ◽  
Sandwich Structures ◽  
Failure Mechanisms ◽  
Composite Beams ◽  
Core Material ◽  
Foam Core ◽  
Sandwich Beams ◽  
Load Carrying Capacity ◽  
The Core ◽  
Load Carrying

In this paper, the load-carrying capacity and failure mechanisms of sandwich beams and panels with elastomeric foam core and composite laminate face sheets are investigated. For this purpose, the flexural behavior of laminated composite beams and panels (applied as face sheets) is firstly investigated under three-point bending and central concentrated loads, respectively. Then, the same examination is conducted for the sandwich beams and panels, in which the proposed elastomeric foam is utilized as the core material. It is shown that the failure mechanisms which are associated to the core in the sandwich structures with crushable foams are not considered in the examined sandwich structures. The collapse of the sandwich specimens, examined here, is observed due to the failure of the skins in some steps. By multi-step collapse of these specimens via separately failure of the top and bottom skins, a considerable amount of energy is absorbed between these steps. Due to non-brittle behavior of the core material under loading, a large compression resistance is observed after failure of the top skin which led to the recovery of the load-carrying capacity in the sandwich beams. A similar behavior for the sandwich panels led to the increase of the ultimate strength after appearance of the failure lines on the top skin. The general outcomes of this investigation promise a good influence for the application of elastomeric foam as core material for sandwich structures.

Flexural Behavior of Six Species of Italian Bamboo

2022 ◽  
Author(s):  
Silvia Greco ◽  
Luisa Molari
Keyword(s):  
Structural Material ◽  
Flexural Strength ◽  
Mechanical Performance ◽  
Functionally Graded ◽  
Flexural Behavior ◽  
Bending Test ◽  
Bamboo Species ◽  
Four Point Bending ◽  
Flexural Ductility ◽  
Graded Material

The good mechanical performance of bamboo, coupled with its sustainability, has boosted the idea to use it as a structural material. In some areas of the world it is regularly used in constructions but there are still countries in which there is a lack of knowledge of the mechanical properties of the locally-grown bamboo, which limits the spread of this material. Bamboo is optimized to resist to flexural actions with its peculiar micro structure along the thickness in which the amount of fibers intensifies towards the outer layer and the inner part is composed mostly of parenchyma. The flexural strength depends on the amount of fibers, whereas the flexural ductility is correlated to the parenchyma content. This study focuses on the flexural strength and ductility of six different species of untreated bamboo grown in Italy. A four-point bending test was carried out on bamboo strips in two different loading configurations relating to its microstructure. Deformation data are acquired from two strain gauges in the upper and lower part of the bamboo beam. Difference in shape and size of Italian bamboo species compared to the ones traditionally used results in added complexity when performing the tests. Such difficulties and the found solutions are also described in this work. The main goal is to reveal the flexural behavior of Italian bamboo as a functionally graded material and to expand the knowledge of European bamboo species toward its use as a structural material not only as culm but also as laminated material.

scholarly journals An Investigation on Mechanical Behavior of Tooth-Plate-Glass-Fiber Hybrid Sandwich Beams

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Honglei Xie ◽  
Li Wan ◽  
Bo Wang ◽  
Haiping Pei ◽  
Weiqing Liu ◽  
...  
Keyword(s):  
Glass Fiber ◽  
Failure Modes ◽  
Bending Strength ◽  
Fibrous Composite ◽  
Strain Energy Release ◽  
Metal Plate ◽  
Plate Glass ◽  
Foam Core ◽  
Sandwich Beams ◽  
Tooth Plate

Tooth-plate-glass-fiber hybrid sandwich (TFS) is a type of sandwich composites fabricated by vacuum-assisted resin infusion process, in which glass fiber facesheets reinforced by metal plate are connected to foam core through tooth nails. Bending properties and interlaminar properties of TFS beams with various foam densities were investigated by flexural tests and DCB (double cantilever beam) tests. The test results showed that by increasing the foam core density from 35 kg/m3 to 150 kg/m3, the peak strength of TFS beams significantly increased by 168% to 258% compared with similar sandwich beams with fibrous composite facesheets. With the change of foam density and span length, the main failure modes are core shear and facesheet indentation beneath the loading roller. The interlaminar strain energy release rates of TFS specimens also increased by increasing the density of the foam. In addition, an analytical model was used to predict the ultimate bending strength of TFS beams, which were in good accordance with the experimental results.

Bending Strength of Cast Materials Reinforced with Hard Particles

2010 ◽  
Vol 457 ◽  
pp. 404-409
Author(s):  
Setsuo Aso ◽  
Hiroyuki Ike ◽  
Ken-Ichi Ohguchi ◽  
Yoshinari Komastu ◽  
Nobuo Konishi
Keyword(s):  
Composite Material ◽  
Bending Strength ◽  
Composite Layer ◽  
Cemented Carbide ◽  
Bending Test ◽  
Spheroidal Graphite ◽  
Four Point Bending ◽  
Hard Particles ◽  
Particle Reinforced Composite ◽  
Insertion Process

Particle reinforcement via the insertion of hard particles is a promising process in materials reinforcing. Particle-reinforced spheroidal graphite martensitic cast iron (SGMC), in which mixed particles of cermet and cemented carbide are dispersed, was achieved by an insertion process. A four-point bending strength test was applied to evaluate the particle composite material. An evaporative pattern process was used on the bending-test specimen to form a composite layer in the central part. Using a combination of three sizes of cermet particles and two sizes of cemented-carbide particles, the bending strength was found to increase with each small-particle combination. The Weibull coefficient m of the four-point bending strength of the particle-reinforced composite material (PRCM) ranged from 4 to 13, and m was large in the specimen with large bending strength.

Environmental Corrosion Resistance of Textile Reinforced Composites in Seawater

2015 ◽  
Vol 813 ◽  
pp. 140-146
Author(s):  
Ning Ning Wang ◽  
Jia Ying Sun ◽  
Cheng Yan Zhu
Keyword(s):  
Corrosion Resistance ◽  
Bending Strength ◽  
Mechanical Performance ◽  
Knitted Fabric ◽  
Reinforced Composites ◽  
Surface Appearance ◽  
Bending Performance ◽  
Average Loss ◽  
Textile Reinforced Composite ◽  
Warp Knitted Fabric

In order to study on mechanical performance as the target of environmental corrosion resistance property, three kinds of glass fiber fabrics like biaxial warp knitted fabric, biaxial stitch-bonded felt and three axial warp knitted fabric were used to prepare textile reinforced composites in five layers laminated structure, which were soaked in seawater environment for 180 days. The result showed that, the surface appearance of textile reinforced composite became muddy and the color became darker, the tensile strength and bending strength of composites decline of the whole with the extension of soak time, the average loss rate of tensile and bending performance are respectively 24.8% and 56.5%, all of these provide the theoretical basis for researching and developing high-quality composite materials.

Experimental and analytical behavior of sandwich composite beams: Comparison of natural and synthetic materials

2016 ◽  
Vol 20 (3) ◽  
pp. 287-307 ◽  
Author(s):  
Pedram Sadeghian ◽  
Dimo Hristozov ◽  
Laura Wroblewski
Keyword(s):  
Composite Beams ◽  
Bending Test ◽  
Synthetic Fiber ◽  
Sandwich Composite ◽  
Flexural Stiffness ◽  
Fiber Types ◽  
Shear Rigidity ◽  
Sandwich Composites ◽  
Core Materials ◽  
Natural And Synthetic

In this study, the flexural behavior of sandwich composite beams made of fiber-reinforced polymer (FRP) skins and light-weight cores are studied. The focus is on the comparison of natural and synthetic fiber and core materials. Two types of fiber materials, namely glass and flax fibers, as well as two types of core materials, namely polypropylene honeycomb and cork, are considered. A total of 105 small-scale sandwich beam specimens (50 mm wide) were prepared and tested under four-point bending. Test parameters were fiber types (flax and glass fibers), core materials (cork ad honeycomb), skin layers (0, 1, and 2 layers), core thicknesses (6–25 mm), and beam spans (150 and 300 mm). The load–deflection behavior, peak load, initial stiffness, and failure mode of the specimens are evaluated. Moreover, the flexural stiffness, shear rigidity, and core shear modulus of the sandwich composites are computed based on the test results of the two spans. An analytical model is also implemented to compute the flexural stiffness, core shear strength, and skin normal stress of the sandwich composites. Overall, the natural fiber and cork materials showed a promising and comparable structural performance with their synthetic counterparts.

scholarly journals Structural Behavior of High Strength Laced Reinforced Concrete One Way Slab Exposed to Fire Flame

2019 ◽  
Vol 5 (12) ◽  
pp. 2747-2761
Author(s):  
Anas Ibrahim Abdullah
Keyword(s):  
Reinforced Concrete ◽  
Bending Strength ◽  
High Strength ◽  
Bending Test ◽  
Structural Members ◽  
Four Point Bending ◽  
Steady State Temperature ◽  
Average Residual ◽  
Fire Flame ◽  
Geometric Layout

In this study, an experimental investigation had conducted for six high strength laced reinforced concrete one-way slabs to discover the behavior of laced structural members after being exposed to fire flame (high temperature). Self-compacted concrete (SCC) had used to achieve easy casting and high strength concrete. All the adopted specimens were identical in their compressive strength of ( , geometric layout 2000 750 150 mm and reinforcement specifics except those of lacing steel content, three ratios of laced steel reinforcement of (0.0021, 0.0040 and 0.0060) were adopted. Three specimens were fired with a steady state temperature of  for two hours duration and then after the specimens were cooled suddenly by spraying water. The simply supported slabs were tested for flexure behavior with two line loads applied in the middle third of the slab (four-point bending test). The average residual percentage of cubic compression strength and splitting tensile strength were 57.5% and 50% respectively. The outcomes indicated that the residual bending strength of the burned slabs with laced ratios (0.0021, 0.004, 0.006) were (72.56, 70.54 and 70.82%) respectively. However; an increase in the deflection was gained to be (11.34, 14.67 and 17.22%) respectively with respect to non-burned specimens.

scholarly journals Mechanical performance of wood under artificial and natural weathering treatments

BioResources ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. 6267-6277
Keyword(s):  
Exposure Time ◽  
Modulus Of Elasticity ◽  
Elastic Limit ◽  
Bending Strength ◽  
Mechanical Performance ◽  
General Information ◽  
Bending Test ◽  
Natural Weathering ◽  
Linear Regression Models ◽  
Artificial Weathering

Natural and artificial weathering treatments were studied to determine the change of wood properties as a function of exposure time. This paper aimed to provide general information about the mechanical performance of wood under natural and artificial weathering treatments and define a relationship between them. The eight strength classes of ABNT NBR 7190 (1997) were considered, in addition to a paired sampling approach. The modulus of elasticity and conventional strength value in static bending, strength in compression parallel to the grain, hardness perpendicular to the grain, and the elastic limit in the static bending test were investigated. Linear regression models for mechanical performances under artificial and natural aging treatments of the exposure time were made and tested using an analysis of variance. According to the results, 360 days of natural weathering provoked a change in mechanical performance of 15.72% that included a decrease in strength and modulus of elasticity and an increase in elastic limit. Twelve hours of the artificial weathering treatment provided the effect of 6.22 days of natural weathering exposure.

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