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

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.

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STRUCTURING OF CURED POLYMERIC COMPOSITE MATERIALS IN A MICROWAVE ELECTROMAGNETIC FIELD

Spravochnik Inzhenernyi zhurnal ◽

10.14489/hb.2021.01.pp.003-009 ◽

2021 ◽

pp. 3-9

Author(s):

I. V. Zlobina

Keyword(s):

Electromagnetic Field ◽

Composite Materials ◽

Polymer Composite ◽

Contact Interaction ◽

Energy Systems ◽

Polymeric Composite ◽

Strength Characteristics ◽

Polymer Composite Materials ◽

Reinforcing Fibers ◽

The Matrix

Based on studies of the microstructure of the matrix of cured polymer composite materials and the area of its contact interaction with reinforcing fibers, the hypothesis of its structuring in the microwave electromagnetic field with an increase in the contact interaction surfaces due to an increase in the number of agglomerates with small transverse dimensions and a decrease in porosity in the macro- and mesopore regions is substantiated. These effects can be used as a basis for increasing the strength characteristics and uniformity of their values after exposure to a microwave electromagnetic field. The results of this work can be used in the development of technologies for finishing hardening of products made of carbon and fiberglass for various transport and energy systems.

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Multilevel Analysis of Strain Rate Effect on Visco-Damage Evolution in Short Random Fiber Reinforced Polymer Composites

International Polymer Processing ◽

10.1515/ipp-2020-4045 ◽

2021 ◽

Vol 36 (2) ◽

pp. 213-218

Author(s):

M. D. D. Boudiaf ◽

L. Hemmouche ◽

M. A. Louar ◽

A. May ◽

N. Mesrati

Keyword(s):

Strain Rate ◽

Damage Evolution ◽

Glass Fibers ◽

Rate Sensitivity ◽

Polymeric Composite ◽

Tensile Tests ◽

Strain Rate Effect ◽

Rate Effect ◽

Fiber Reinforced ◽

Stress Levels

Abstract In this study, the strain rate sensitivity of a discontinuous short fiber reinforced composite and the strain rate effect on the damage evolution are investigated. The studied material is a polymeric composite with a polyamide 6.6 matrix reinforced with oriented randomly short glass fibers at a 50% weigh ratio (PA6.6GF50). Tensile tests at low and high strain rate are conducted. In addition, interrupted tensile tests are carried out to quantify the damage at specific stress levels and strain rates. To perform the interrupted tensile tests, an intermediate fixture is realized via double notched mechanical fuses with different widths designed to break at suitable stress levels. The damage is estimated by the fraction of debonded fibers and matrix fractures. Based on the experimental observations, it is concluded that the ultimate stress and strain, and the damage threshold are mainly governed by the strain rate. Furthermore, it is established that the considered composite has a non-linear dynamic behavior with a viscous damage nature.

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Influence of Rate of Strain and Temperature on Yield Stresses of Mild Steel

Journal of Applied Mechanics ◽

10.1115/1.4009394 ◽

1944 ◽

Vol 11 (4) ◽

pp. A211-A218

Author(s):

M. J. Manjoine

Keyword(s):

Mild Steel ◽

Yield Stress ◽

Strain Aging ◽

Room Temperature ◽

Tensile Tests ◽

Ultimate Stress ◽

Strain Rates ◽

Discontinuous Yielding

Abstract This paper describes the influence of rate of strain and temperature on the yield stresses of mild steel. Tensile tests are reported for room temperature, 200, 400, and 600 C, at rates of strain which vary from 10−8 to 103 per sec. The results of these tensile tests are plotted to show more clearly the effects of strain-aging on the yield stresses and ultimate stress. The comparison of the yield stress at various strain rates permits an analysis of the influence of strain. The conditions necessary for discontinuous yielding are described and compared with test experiences.

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Coupling effect of strain rate and temperature on tensile damage mechanism of polyphenylene sulfide reinforced by glass fiber (PPS/GF30)

Journal of Thermoplastic Composite Materials ◽

10.1177/0892705720944229 ◽

2020 ◽

pp. 089270572094422

Author(s):

Mohammadali Shirinbayan ◽

Joseph Fitoussi ◽

Farid Kheradmand ◽

Arash Montazeri ◽

Peiyuan Zuo ◽

...

Keyword(s):

Strain Rate ◽

Glass Fiber ◽

High Strain ◽

Coupling Effect ◽

Damage Mechanism ◽

Tensile Tests ◽

Ultimate Stress ◽

Polyphenylene Sulfide ◽

Stress And Strain ◽

Strain Rates

Influence of loading temperature on the damage mechanism of polyphenylene sulfide (PPS) reinforced by glass fiber (PPS/GF30) under tension was experimentally studied from quasi-static (QS) to high strain rates. Two kinds of PPS/GF30 samples were prepared: PPS-0° and PPS-90° (correspond to fibers oriented parallel and perpendicular to the injection direction, respectively). After microscopic observation and thermomechanical characterizations by dynamic mechanical analysis, tensile tests up to failure with strain rates varying from 10−3 s−1 to 100 s−1 have been carried out at 25°C and 120°C with regard to PPS/GF30 glass transition temperature. To achieve the coupling effect of high strain rate and high temperature, a special chamber was designed to install on the servo-hydraulic machine. The results of QS tensile tests confirm the significant effect of fiber orientation and temperature on the Young’s modulus, the ultimate stress, and strain. High strain tensile test results showed that the PPS/GF30 composite is strain rate dependent at both temperatures. The results indicated that Young’s modulus remains constant by strain rate increasing at both temperatures while ultimate stress and strain are increased. No significant damage has been observed at 25°C in QS loading, whereas the macroscopic damage variable is increased to 20% at 120°C. Debonding at the fiber–matrix interface is the main damage mechanism at 120°C.

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Experimental System and Validation for Energy-Based Characterization

Volume 2: 31st Computers and Information in Engineering Conference, Parts A and B ◽

10.1115/detc2011-48902 ◽

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.

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1106 Tensile Tests on Steels and Aluminum alloys in a Wide Range of Strain Rates by High Speed Material Testing System with Sensing Block

The Proceedings of Conference of Kansai Branch ◽

10.1299/jsmekansai.2000.75._11-11_ ◽

2000 ◽

Vol 2000.75 (0) ◽

pp. _11-11_-_11-12_

Author(s):

Takeshige MACHIGAKI ◽

Yoshitaka ASHIDA ◽

Koji MIMURA ◽

Tsutomu UMEDA ◽

Shinji TANIMURA

Keyword(s):

Aluminum Alloys ◽

High Speed ◽

Tensile Tests ◽

Material Testing ◽

Testing System ◽

Strain Rates ◽

Wide Range

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Ultimate Strength and Plasticity of Magnesium Alloy under Different Temperatures and Strain Rates

Materials Science Forum ◽

10.4028/www.scientific.net/msf.686.225 ◽

2011 ◽

Vol 686 ◽

pp. 225-229

Author(s):

Bin Chen ◽

Da Gang Yin ◽

Quan Yuan ◽

Ji Luo ◽

Ding Fei Zhang ◽

...

Keyword(s):

Magnesium Alloy ◽

Ultimate Strength ◽

Fracture Stress ◽

Tensile Tests ◽

Material Testing ◽

Testing System ◽

Strain Rates ◽

Az61 Magnesium Alloy ◽

Different Temperatures ◽

Strength And Plasticity

A series of tensile tests of AZ61 magnesium alloy were conducted using Gleeble-1500 thermal-mechanical material testing system to learn the effect of the test temperatures and strain rates on the mechanical properties of the alloy. It is indicated that the higher the temperature, the lower the ultimate strength and fracture stress, and the larger the plasticity. It is also revealed that the larger the strain rate is, the higher the ultimate strength of the specimens will be, and the larger the plasticity of the specimens will be. The failure mechanism of the material under high temperature was also analyzed based on the fracture observation. It shows that the high temperatures will induce microvoids or microflaws in the material.

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Discrete ply modelling of open hole tensile tests

Composite Structures ◽

10.1016/j.compstruct.2014.03.031 ◽

2014 ◽

Vol 113 ◽

pp. 369-381 ◽

Cited By ~ 27

Author(s):

Victor Achard ◽

Christophe Bouvet ◽

Bruno Castanié ◽

Clément Chirol

Keyword(s):

Tensile Tests ◽

Open Hole

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Rhinological Status of Patients with Nasolacrimal Duct Obstruction

International Archives of Otorhinolaryngology ◽

10.1055/s-0041-1730018 ◽

2021 ◽

Author(s):

Vasily D. Yartsev ◽

Eugenia L. Atkova ◽

Eugeniy O. Rozmanov ◽

Nina D. Yartseva

Keyword(s):

Rank Correlation ◽

Statistical Processing ◽

Correlation Method ◽

Nasolacrimal Duct ◽

Nasolacrimal Duct Obstruction ◽

Control Group ◽

Duct Obstruction ◽

Rank Correlation Method ◽

Significant Difference ◽

The Difference

Abstract Introduction Studying the state of the nasal cavity and its sinuses and the morphometric parameters of the inferior nasal conchae, as well as a comparative analysis of obtained values in patients with primary (PANDO) and secondary acquired nasolacrimal duct obstruction (SALDO), is relevant. Objective To study the rhinological status of patients with PANDO) and SALDO). Methods The present study was based on the results of computed tomography (CT) dacryocystography in patients with PANDO (n = 45) and SALDO due to exposure to radioactive iodine (n = 14). The control group included CT images of paranasal sinuses in patients with no pathology (n = 49). Rhinological status according to the Newman and Lund-Mackay scales and volume of the inferior nasal conchae were assessed. Statistical processing included nonparametric statistics methods; χ2 Pearson test; and the Spearman rank correlation method. Results The difference in values of the Newman and Lund-Mackay scales for the tested groups was significant. A significant difference in scores by the Newman scale was revealed when comparing the results of patients with SALDO and PANDO. Comparing the scores by the Lund-Mackay scale, a significant difference was found between the results of patients with SALDO and PANDO and between the results of patients with PANDO and the control group. Conclusion It was demonstrated that the rhinological status of patients with PANDO was worse than that of patients with SALDO and of subjects in the control group. No connection was found between the volume of the inferior nasal conchae and the development of lacrimal duct obstruction.

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