scholarly journals Discrete ply modelling of open hole tensile tests

2014 ◽  
Vol 113 ◽  
pp. 369-381 ◽  
Author(s):  
Victor Achard ◽  
Christophe Bouvet ◽  
Bruno Castanié ◽  
Clément Chirol
Keyword(s):  
Tensile Tests ◽  
Open Hole

Experimental System and Validation for Energy-Based Characterization

2011 ◽  
Author(s):  
Jan Wei Pan ◽  
Jinquan Cheng ◽  
Tomonari Furukawa ◽  
Athanasios P. Iliopoulos ◽  
John G. Michopoulos
Keyword(s):  
Elastic Constants ◽  
Testing Machine ◽  
Experimental System ◽  
Tensile Tests ◽  
Recursive Estimation ◽  
Sensor Data ◽  
External Work ◽  
Measurement Results ◽  
Uniaxial Testing ◽  
Open Hole

This paper presents the experimental system and experimental validation of an energy-based characterization for the identification of elastic constants. Unlike the standard uniaxial testing machine, which uses a contact strain sensor such as extensometer, the developed system uses a non-contact optic sensor as an advantage to measure and derive external work and strain measurements for characterizing the elastic constants. To investigate the validity of the energy-based characterization, a graphical user interface and the experimental system were developed for the tensile tests of aluminum open-hole specimens. During the validation, the means and variances of the characterization results were analyzed. The reliability of its recursive estimation was further investigated by the convergence of covariance at every new measurement. Results showed that the recursive estimation allows identification of elastic constants of a test coupon at every acquisition of sensor data in an online manner. The identification of all the constants during deformation thus demonstrated the overall validity and efficiency of the energy-based characterization.

Effects of ply thickness and 0°-layer ratio on failure mechanism of open-hole and filled-hole tensile tests of thin-ply composite laminates

2021 ◽  
pp. 114926
Author(s):  
Ryoma Aoki ◽  
Ryo Higuchi ◽  
Tomohiro Yokozeki ◽  
Kazuyuki Aoki ◽  
Shigekazu Uchiyama ◽  
...  
Keyword(s):  
Failure Mechanism ◽  
Composite Laminates ◽  
Tensile Tests ◽  
Open Hole

scholarly journals Evaluation of the Sensitivity of Various Reinforcement Patterns for Structural Carbon Fibers to Open Holes during Tensile Tests

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4287
Author(s):  
Elena Strungar ◽  
Dmitrii Lobanov ◽  
Valery Wildemann
Keyword(s):  
Statistical Processing ◽  
Correlation Method ◽  
Polymeric Composite ◽  
Tensile Tests ◽  
Ultimate Stress ◽  
Testing System ◽  
Fiber Tension ◽  
Reinforcing Fibers ◽  
Open Hole ◽  
Structural Carbon

This paper is devoted to the experimental study of polymeric composite specimens, with various types of reinforcement, in order to evaluate the breaking strength of specimens with open holes when undergoing uniaxial compression and tensile tests. Four types of interlaced 3D woven preforms were considered (orthogonal, orthogonal combined, with pairwise inter-layer reinforcement, and with pairwise inter-layer reinforcement and a longitudinal layer), with a layered preform used for comparison. Tensile tests of solid specimens without a hole, under ASTM D 3039, and of specimens with an open hole, under ASTM D 5766, were carried out using the Instron 5989 universal electromechanical testing system. Movements and strains on the specimen surface were recorded using a Vic-3D contactless optical video system and the digital images correlation method (DIC). For all the series of carbon fiber tension specimens, strain and stress diagrams, mechanical characteristics, and statistical processing for 10 specimens were obtained. The paper evaluated deformation fields for certain points in time; the obtained fields showed an irregular distribution of deformation and dependency on types of reinforcing fibers. A coefficient of strength variation is introduced, which is defined as a ratio of the ultimate stress limits obtained on solid samples with and without open holes. Within the framework of ASTM D 5766, when calculating the ultimate stress, the hole is not taken into account, and the paper shows that for certain structures a hole cannot be excluded. The hole size must not be neglected when calculating the ultimate stress.

Influence of Shelf Life on Mechanical Properties of Glass Fibre Reinforced Composites

2021 ◽  
Vol 58 (1) ◽  
pp. 131-141
Author(s):  
Mihaela Raluca Condruz ◽  
Ionut Sebastian Vintila ◽  
Tiberius Florian Frigioescu ◽  
Alexandru Paraschiv ◽  
Andrei Mandoc ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shelf Life ◽  
Glass Fibre ◽  
Tensile Tests ◽  
Reinforced Composites ◽  
Plane Shear ◽  
Open Hole ◽  
Glass Fibre Reinforced ◽  
Glass Fibre Reinforced Composites ◽  
Fibre Reinforced Composites

The present paper was focused on studying the influence of shelf life of an epoxy matrix on the mechanical properties of glass fibre reinforced composites. For the study, two types of the same epoxy system were used, one during its shelf life and one out of its shelf life. The reinforcement used consisted in E-glass fibre fabric. Mechanical investigations were realized in order to compare the materials in terms of loss of mechanical strength and elastic properties. Therefore, three mechanical tests were performed: tensile tests, in-plane shear and open-hole tensile tests. The results showed that the shelf life affects the mechanical properties of the polymeric composite. A decrease of 24% in tensile strength was recorded along with a 28% decrease of the in-plane shear strength and 55% of open-hole tensile strength for the composite manufactured with the out of shelf life epoxy system compared with the other composite. An overall reduction of mechanical strength and elastic properties of the composite material was observed, primarily due to polymeric matrix degradation, which after long periods it could be prone to brittleness and susceptible to delamination and fracture. The thermogravimetric analysis showed that thermal induced changes are happening at a higher speed in the out of shelf life composite, a lower mass loss being registered for new epoxy composite.

Calculation And Experimental Substantiation Of Optimal Design Of The Welded Joint Of Plates On Соver Plates

2020 ◽  
pp. 17-24
Keyword(s):  
Welded Joint ◽  
Experimental Studies ◽  
Engineering Calculation ◽  
Tensile Tests ◽  
Physical Nonlinearity ◽  
Steel Plates ◽  
Optimal Parameters ◽  
Actual Problem ◽  
Numerical Research ◽  
Cover Plates

The article is devoted to the actual problem of assigning optimal parameters for connecting steel plates on cover plates with angular welds that are widely used in construction practice. The article presents the results of a comprehensive study of operation of a welded assembly of the plates connection on cover plates. An algorithm is proposed for determining the optimal parameters of a welded joint with fillet welds on the cover plates, which makes it possible to obtain a strength balanced connection. The results of full-scale tensile tests of models were presented. These results confirmed the correctness of the assumed design assumptions, and made it possible to obtain a form of destruction, not characteristic and not described in the normative literature, expressed by cutting the main elements along the length of the overlap in the joint. The possibility of such a form of destruction was confirmed by the results of numerical research in a nonlinear formulation. The optimal parameters of the nodal welded joint determined by engineering calculation are confirmed by experimental studies, as well as by the results of numerical experiments on models of calculation schemes, taking into account the physical nonlinearity of the material operation. The obtained dependence for determining the bearing capacity of the joint by the cut-off mechanism and the expression for limiting the overlap length of the cover plates will make it possible to predict the nature of the fracture and design equally strong joints.

Application of machine learning methods for automatic interpretation of open hole logging data

2020 ◽  
pp. 44-47
Author(s):  
M.A. Basyrov ◽  
◽  
A.V. Akinshin ◽  
I.R. Makhmutov ◽  
Yu.D. Kantemirov ◽  
...  
Keyword(s):  
Machine Learning ◽  
Learning Methods ◽  
Machine Learning Methods ◽  
Automatic Interpretation ◽  
Open Hole

Regularities and properties of instrumented indentation diagrams obtained by ball-shaped indenter

2020 ◽  
Vol 86 (5) ◽  
pp. 43-51
Author(s):  
V. M. Matyunin ◽  
A. Yu. Marchenkov ◽  
N. Abusaif ◽  
P. V. Volkov ◽  
D. A. Zhgut
Keyword(s):  
Yield Strength ◽  
Ultimate Strength ◽  
Elastoplastic Deformation ◽  
Elastic Limit ◽  
Tensile Tests ◽  
Indentation Load ◽  
International Standards ◽  
Instrumented Indentation ◽  
Indentation Methods ◽  
Special Points

The history of appearance and the current state of instrumented indentation are briefly described. It is noted that the materials instrumented indentation methods using a pyramid and ball indenters are actively developing and are currently regulated by several Russian and international standards. These standards provide formulas for calculating the Young’s modulus and hardness at maximum indentation load. Instrumented indentation diagrams «load F – displacement α» of a ball indenter for metallic materials were investigated. The special points on the instrumented indentation diagrams «F – α» loading curves in the area of elastic into elastoplastic deformation transition, and in the area of stable elastoplastic deformation are revealed. A loading curve area with the load above which the dF/dα begins to decrease is analyzed. A technique is proposed for converting «F – α» diagrams to «unrestored Brinell hardness HBt – relative unrestored indent depth t/R» diagrams. The elastic and elastoplastic areas of «HBt – t/R» diagrams are described by equations obtained analytically and experimentally. The materials strain hardening parameters during ball indentation in the area of elastoplastic and plastic deformation are proposed. The similarity of «HBt – t/R» indentation diagram with the «stress σ – strain δ» tensile diagrams containing common zones and points is shown. Methods have been developed for determining hardness at the elastic limit, hardness at the yield strength, and hardness at the ultimate strength by instrumented indentation with the equations for their calculation. Experiments on structural materials with different mechanical properties were carried out by instrumented indentation. The values of hardness at the elastic limit, hardness at the yield strength and hardness at the ultimate strength are determined. It is concluded that the correlations between the elastic limit and hardness at the elastic limit, yield strength and hardness at the yield strength, ultimate tensile strength and hardness at the ultimate strength is more justified, since the listed mechanical characteristics are determined by the common special points of indentation diagrams and tensile tests diagrams.

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