Correlation of Tensile and Bending Strength of Composites With a Circular Hole

1996 ◽  
Vol 118 (4) ◽  
pp. 542-547
Author(s):  
Yi Zhao ◽  
Su-Seng Pang ◽  
Chihdar Yang
Keyword(s):  
Circular Hole ◽  
Bending Strength ◽  
Elliptic Hole ◽  
Complex Nature ◽  
Orthotropic Plates ◽  
Element Analysis ◽  
Bending Tests ◽  
Four Point Bending ◽  
Circular Holes ◽  
Good Agreement

While significant studies have been conducted on composites containing a circular or an elliptic hole under tensile loading, few investigations have been reported on notched composites under bending due to the complex nature of the problem. In this paper, a correlation of strengths of orthotropic plates containing a circular hole under tension and bending has been proposed based on Lekhnitskii’s solutions for infinite width plates. Finite element analysis has been performed to verify the theoretical correlation. Uniaxial tension and four-point bending tests have also been conducted on Scotchply samples with circular holes of various sizes. A good agreement has been observed among the theoretical, FEA, and experimental results.

scholarly journals Switchable stiffness morphing aerostructures based on granular jamming

2019 ◽  
Vol 30 (17) ◽  
pp. 2581-2594 ◽  
Author(s):  
J David Brigido-González ◽  
Steve G Burrow ◽  
Benjamin KS Woods
Keyword(s):  
Flexural Rigidity ◽  
Fish Bone ◽  
Nonlinear Material ◽  
Element Analysis ◽  
Bending Tests ◽  
Four Point Bending ◽  
External Loads ◽  
Structural Solutions ◽  
Different Levels ◽  
Good Agreement

One of the persistent challenges facing the development of morphing aerostructures is the need to have material and structural solutions which provide a compromise between the competing design drivers of low actuation energy and high stiffness under external loads. This work proposes a solution to this challenge in the form of a novel switchable stiffness structural concept based on the principle of granular jamming. In this article, the concept of using granular jamming for controlling stiffness is first introduced. Four-point bending tests are used to obtain the flexural rigidity and bending stiffness of three different granular materials under different levels of applied vacuum loading. Nonlinear finite element analysis simulations using experimentally derived nonlinear material properties show good agreement with experiment. A specific application of this concept is then proposed based on the Fish Bone Active Camber morphing airfoil. A unit cell of this concept is built, tested and analysed, followed by the first prototype of a complete switchable stiffness Fish Bone Active Camber morphing airfoil, which is experimentally shown to be able to achieve an increase in stiffness of up to 300% due to granular jamming.

Experimental Assessment of the Glued Laminated Timber Beams in 4-Point Bending Tests and Photoelastic Coating Technique

2015 ◽  
Vol 240 ◽  
pp. 155-160
Author(s):  
Ludomir J. Jankowski ◽  
Tomasz Nowak
Keyword(s):  
Cross Sections ◽  
Bending Strength ◽  
Experimental Assessment ◽  
Bending Tests ◽  
Coating Technique ◽  
Four Point Bending ◽  
Photoelastic Coating ◽  
Glued Laminated Timber ◽  
Measurement Results ◽  
Good Agreement

The paper presents the results of investigation on seven glued laminated timber (GL24h class) bending beams. Bending strength and modulus of elasticity were determined. The beams were tested for four-point bending by loading them at a constant speed deflection. The strain gauge method and photoelastic coating technique were applied for strain distributions determination in selected cross-sections of the beams. Good agreement of the measurement results was obtained with both techniques. Application of the photoelastic coating technique enabled more detailed analysis of the beams failure mode, including timber defects influence on the strain distributions.

Failure of Foam Core Sandwiches: Numerical Simulation by Microplane Model

2000 ◽  
Author(s):  
Zdeněk P. Bažant ◽  
Michele Brocca
Keyword(s):  
First Principles ◽  
Constitutive Law ◽  
Geometrically Nonlinear ◽  
Element Analysis ◽  
Microplane Model ◽  
Bending Tests ◽  
Three Point Bending ◽  
Closed Cell ◽  
Physical Phenomena ◽  
Good Agreement

Abstract The paper presents a new constitutive model for closed-cell polymeric foams. The model is of the microplane type. In this model, the constitutive law is characterized in terms of vectors rather then tensors. The conceptual simplicity of this ‘first-principles’ approach makes it possible to base the model more directly on the physical phenomena occurring in the microstructure, in this case the elastic bending of the cells idealized as spheres in contact. The model is then employed in a finite element analysis of three point bending tests of sandwich beams failing by core indentation. Good agreement of the numerical results with the experimental observations is achieved. The softening and size effect engendered by the reduction of tangential bending stiffness due to the geometrically nonlinear effect of core indentation is discussed.

scholarly journals Flexural Performance Evaluation of Novel Wide Long-Span Composite Beams Used to Construct Lower Parking Structures

2019 ◽  
Vol 12 (1) ◽  
pp. 98
Author(s):  
Yun-Chul Choi ◽  
Doo-Sung Choi ◽  
Keum-Sung Park ◽  
Kang-Seok Lee
Keyword(s):  
Flexural Strength ◽  
Composite Beams ◽  
Steel Beams ◽  
Test Results ◽  
Element Analysis ◽  
Bending Tests ◽  
Flexural Performance ◽  
Long Span ◽  
Global And Local ◽  
Good Agreement

Efficient parking structures are urgently required in Korea. The design of parking structures more than 8 m in height is difficult because both fire and seismic resistance must be considered. Existing designs are uneconomical and conservative. However, the design of parking structures less than 8 m in height is relatively simple and there are few restrictions to the construction. It is essential to optimize the design of parking structures less than 8 m in height. Here, we describe novel wide long-span composite beams that reduce the story height of low parking structures. The flexural capacity of seven of the beams was evaluated; all beams were loaded at two points prior to monotonic bending tests. We also performed finite element analysis (FEA) based on the material properties of the test specimens, and compared the results to those of the structural tests. The flexural strength of the wide composite steel beams increased by approximately 20% as the steel thickness rose by 3 mm, from 6 to 9 mm. The rebar shape (triangular or rectangular) did not affect flexural strength. The flexural strength of beams without rebar was 10% less than that of beams with rebar. The FEA and test results were in good agreement. The section plastic moments were free from global and local instability.

Cement Composite Reinforced with Synthetic Fibers: Comparison of Three-Point and Four-Point Bending Test Results

2016 ◽  
Vol 827 ◽  
pp. 332-335 ◽  
Author(s):  
Jaroslav Topič ◽  
Jan Bartoš ◽  
Lubomír Kopecký ◽  
Karel Šeps ◽  
Zdeněk Prošek ◽  
...  
Keyword(s):  
Bending Strength ◽  
Cement Composite ◽  
Bending Test ◽  
Test Results ◽  
Recycled Pet ◽  
Bending Tests ◽  
Synthetic Fibers ◽  
Four Point Bending ◽  
Pet Fibers ◽  
Four Point Bending Test

Presented article deals with the influence of PET fiber production on the bending strength of cement-based composite when incorporated into the fresh mortar, and comparison of results of 3-point and 4-point bending test. Cement paste samples were reinforced with 2 wt. % of primary or recycled PET fibers. The bending test was performed on prismatic samples with dimension of 40 × 40 × 160 mm. It was found that samples with recycled PET fibers, compared to primary ones, exhibit a decrease in bending strength. In the case of 4-point bending tests, the samples with recycled PET fibers exhibited higher bending strength than reference samples without any fibers. However, in the case of 3-point bending tests, the samples with recycled PET fibers had lower bending strength than the reference ones. The results suggest that recycled PET fibers could be used as an alternative to reinforce cement-based composites.

Stresses around large circular holes in uniform circular cylindrical shells

1982 ◽  
Vol 17 (1) ◽  
pp. 9-12 ◽  
Author(s):  
J W Bull
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cylindrical Shell ◽  
Axial Compression ◽  
Cylindrical Shells ◽  
Element Analysis ◽  
Three Point Bending ◽  
Circular Holes ◽  
Circular Cylindrical Shells ◽  
Good Agreement

An experimental and finite element analysis of a uniform cylindrical shell with a large circular cut-out is presented. In this analysis three hole sizes are considered, namely μ = 2.037, 4.084, and 6.344 (where μ = {[12(1 - y2)]1/4/2} × [ a/( Rt)1/2]), for loadings of axial compression, torsion and three point bending. The experimental results are the only ones available for cylindrical shells with large values of μ (except for one graph by Savin (1)†), while for three point bending there is no previously published theoretical or analytical results. Good agreement is found between the calculated and experimental stresses around the holes.

Bending strength of ceramic compounds bonded with silicate-based glass solder

2021 ◽  
Vol 63 (7) ◽  
pp. 593-598
Author(s):  
Jan-Oliver Sass ◽  
Abdessalam Jakobi ◽  
Aurica Mitrovic ◽  
Cornelia Ganz ◽  
Jennifer Wilken ◽  
...  
Keyword(s):  
Bending Strength ◽  
Ethanol Treatment ◽  
Bending Tests ◽  
Bonding Parameters ◽  
Soldering Process ◽  
Four Point Bending ◽  
Process Pressure ◽  
Monolithic Zirconia ◽  
Ceramic Compounds

Abstract In the field of dental technology, the length of ceramic pontics is limited to avoid mechanical failure. To reduce thermal-induced residual stress within the ceramic, using smaller subcomponents and subsequent bonding with silicate-based glass solder may be a favorable approach. Thus, the bending strength of zirconia compounds bonded with different silicate-based glass solders was investigated. For this purpose, rectangular specimens made of zirconia were bonded by glass solder. Parameters such as the scarf angle (45° and 90°), two different glass solders, as well as the soldering process (pressure and surface treatment) were varied. All specimens were subjected to quasi-static four-point bending tests according to DIN EN ISO 843-1. Additionally, the quality of the glass solder connection was evaluated using μCT and fractography. In the present study, zirconia compounds were sucessful bonded of zirconia compounds using silicate-based glass solder was. No significant differences in terms of bending strength were observed with respect to the different bonding parameters analyzed. The highest bending strength of 130.6 ± 50.5 MPa was achieved with a 90° scarf angle combined with ethanol treatment of the specimens before soldering and an additional application of a pressure of 2 bars in a dental pressure pot before subsequent soldering. Nevertheless, the bending strengths were highly decreased when compared to monolithic zirconia specimens (993.4 ± 125.5 MPa).

Structural Properties of Immature Canine Bone

1981 ◽  
Vol 103 (4) ◽  
pp. 232-238 ◽  
Author(s):  
P. A. Torzilli ◽  
K. Takebe ◽  
A. H. Burstein ◽  
K. G. Heiple
Keyword(s):  
Bone Tissue ◽  
Structural Properties ◽  
Material Properties ◽  
Growth Process ◽  
Bending Strength ◽  
Developmental Process ◽  
Long Bones ◽  
Bending Tests ◽  
Four Point Bending ◽  
Tissue Material

Structural properties of growing canine long bones were determined from three and four-point bending tests. Mechanical and geometric properties were found to follow a biphasic growth process, with a rapid increase in bending strength and moment of inertia from 1 to 24 wk of age and a substantially decreased rate thereafter to maturity. Predicted bone tissue material properties were also found to follow this biphasic developmental process.

scholarly journals Experimental research on load bearing capacity of adhesively jointed beech timber lamellas

2019 ◽  
Author(s):  
Eva Šuhajdová ◽  
Miloslav Novotný ◽  
Jan Pěnčík ◽  
Karel Šuhajda
Keyword(s):  
Bending Strength ◽  
Wood Products ◽  
Finger Joint ◽  
Polyurethane Adhesive ◽  
Load Bearing Capacity ◽  
Local Conditions ◽  
The Czech Republic ◽  
Bending Tests ◽  
Four Point Bending ◽  
Engineered Wood Products

The aim of this work was to verify behavior of a beech timber finger-joint in local conditions in the Central Europe. The samples were produced with a glued joint with the finger length of 23 mm according to standard ČSN EN 14 080. Commonly used polyurethane adhesive for production of engineered wood products in the Czech Republic was used. The samples were loaded by destructive four-point bending tests according to standard ČSN EN 408, and the achieved bending strength was statistically evaluated and compared with results of non-glued samples. The results showed that bending strength of lamellas with a finger-joint reached about 65% of the strength of samples without a joint, and the failure of lamellas occurred in most cases at the joint.

Bending Properties and Finite Element Modeling of Biaxial Weft Knitted Composites

2012 ◽  
Author(s):  
O. Demircan ◽  
Y. Hamada ◽  
T. Kosui ◽  
A. Nakai ◽  
H. Hamada
Keyword(s):  
Finite Element ◽  
Composite Structures ◽  
Knitted Fabric ◽  
Bending Properties ◽  
Element Analysis ◽  
Bending Tests ◽  
Bending Property ◽  
Weft Knitted Fabric ◽  
Complex Construction ◽  
Good Agreement

In order to improve the mechanical properties of weft knitted fabric, straight yarns both in weft and warp directions can be integrated. These types of reinforcements are called biaxial weft knitted structures. Finite element analysis is a well known method for analysis of complex construction with complex material properties. Therefore, we wanted to use FEM to express the possibility of prediction of bending properties of complex biaxial weft knitted (BWK) composite structures. The purpose of this study is to investigate bending properties of BWK composites by experimentally and numerically. Two types of six plies composite panels, which include fiber contents, such as glass-glass-aramid and aramid-aramid-aramid, were fabricated by hand lay-up method. After production of composites, bending tests had been conducted on specimens. Glass-glass-aramid composites exhibited superior bending property than aramid-aramid-aramid specimens. The good agreement between the experimental results and numerical results validated the applicability of finite-element method for biaxial weft knitted composites.

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