scholarly journals Fracturing and Damage of 3D-Printed Materials with Two Intermittent Fissures under Compression

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1607 ◽  
Author(s):  
Duan Zhang ◽  
Qianqian Dong
Keyword(s):  
Failure Modes ◽  
Failure Process ◽  
Sample Surface ◽  
Initial Position ◽  
Image Correlation ◽  
Tensile Failure ◽  
Composite Failure ◽  
Bridge Damage ◽  
3D Printed ◽  
Printed Materials

The crack propagation and failure of 3D-printed samples with prefabricated K–S fissures (a kinked fissure and a straight fissure) were observed under uniaxial compression, and the strain and displacement of the sample surface were quantified by the digital image correlation (DIC) method. The experimental results show that the branch inclination angle of the kinked fissure is an important factor affecting the crack initial position, and the evolution of the strain field during the failure process of the sample can better reflect the cracking law of the internal fissures. Furthermore, two coalescence modes are classified: Mode I is a tension–shear composite failure formed by the penetration of the tension–shear composite crack; Mode II is a tensile failure that penetrates the whole samples during the failure process without rock bridge damage. In addition, the numerical simulation results were well consistent with the cracking and failure modes.

scholarly journals Research on Failure Characteristics of Concrete Three-Point Bending Beams with Preexisting Cracks in Different Positions Based on Numerical Simulation

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Liuqun Zhao ◽  
Li Zheng ◽  
Hui Qin ◽  
Tiesuo Geng ◽  
Yonggang Tan ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Failure Process ◽  
Engineering Application ◽  
Tensile Failure ◽  
Engineering Structures ◽  
Failure Characteristics ◽  
Three Point Bending ◽  
Wide Range

Concrete three-point bending beams with preexisting cracks are widely used to study the growth process of I-II mixed mode cracks. Studying the failure characteristics of preexisting cracks at different locations on concrete three-point bending beams not only has important scientific significance but also has a wide range of engineering application backgrounds in the safety assessment of engineering structures. In this paper, through several numerical experiments, the influence of preexisting cracks at different positions on the failure characteristics of concrete three-point bending beams is studied, and three typical failure modes are obtained. The failure process of the specimens with three typical failure modes is discussed in detail, and it is pointed out that the crack failure mode is tensile failure. The change trends of bearing capacity, acoustic emission quantity, and acoustic emission energy of three typical failure modes are analyzed. The maximum bearing capacity, the maximum acoustic emission quantity, and energy of three failure modes of concrete three-point bending beams generally show an increasing trend.

Experimental Investigation on Adhesive Bonded Joints of Carbon Fiber Composite Laminates Containing Disbond Defect

2017 ◽  
Author(s):  
Ping Qiu ◽  
Jianfeng Shi ◽  
Jinyang Zheng
Keyword(s):  
Carbon Fiber ◽  
Adhesive Bonding ◽  
Phased Array ◽  
Failure Modes ◽  
Fiber Composite ◽  
Failure Process ◽  
Tensile Load ◽  
Lap Joints ◽  
Adhesive Joints ◽  
Image Correlation

Adhesive bonding technology is widely used for connecting composite pipes recent years, for the adhesive joints have many advantages such as weight reduction, ease of manufacture, and more importantly, uniform stress distribution and less stress concentration within the joint region. Nevertheless, one of the limitations of adhesive joints is the difficulty in predicting the joint strength due to the presence of defects in the adhesive due to improper curing process. This paper presents an experimental study of single-lap joints with disbond defects at the adherend-adhesive interface. Different sets of adhesively-bonded singlelap joints containing varied disbond conditions were prepared and tested. The joints used carbon fiber reinforced polymer (CFRP) laminates as substrates and epoxy resin as adhesive, with ultrathin aluminum foil (10um) as disbond defects in different sizes and locations. The full deformation fields were measured using the digital image correlation (DIC) method. The samples were subjected to tensile load till failure to determine the bond strength. Before the tensile test, the defective adhesive joints were detected by a phased-array ultrasonic instrument to identify the bond-line quality of joints. The results show that the disbond defects can be detect by ultrasonic phased-array technique, and the detriment of disbond defect to the failure process can be observed and recorded by DIC system. Based on the findings, the failure modes and failure mechanism of bonded CFRP joint were further discussed.

scholarly journals Bedding Plane Effects on Mechanical Behavior of Surrounding Rock in Mountain Tunneling

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Shuang You ◽  
Jincui Sun ◽  
Hongtao Wang
Keyword(s):  
Failure Modes ◽  
Bedding Plane ◽  
Tensile Failure ◽  
Mechanical Parameters ◽  
Test Results ◽  
Compression Tests ◽  
Composite Failure ◽  
Layered Rock ◽  
Testing Data ◽  
Weak Plane

The layered rock showed the characteristics in Mountain tunnel, Yunnan. A series of uniaxial compression tests and variable angle shear tests were carried out, and the aim was to investigate the effect of the bedding on its mechanical parameters and failure modes. The test results show that the uniaxial compressive strength, elastic modulus, and Poisson's ratio of layered rock present a U-shaped distribution with the increase in bedding orientation from 0° to 90°. All of them have a maximum when the bedding orientation is 0° and a minimum when the bedding orientation is 45°. The failure modes of layered rock can be summarized into three types: the fracture tensile failure parallel to the weak plane of bedding; the shear slip failure along bedding weak plane; and tension-shear composite failure between bedding weak plane and matrix. Based on the testing data and analysis results, it can be concluded that the layered rock specimen with different bedding orientations is an important reason for the anisotropy of mechanical parameters and failure modes.

scholarly journals Scaling in biomechanical experimentation: a finite similitude approach

2018 ◽  
Vol 15 (143) ◽  
pp. 20180254 ◽  
Author(s):  
Raul Ochoa-Cabrero ◽  
Teresa Alonso-Rasgado ◽  
Keith Davey
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Image Correlation ◽  
Supporting Evidence ◽  
Maximum Difference ◽  
Resource Limitations ◽  
Novel Approach ◽  
Finite Element Package ◽  
3D Printed ◽  
Printed Materials

Biological experimentation has many obstacles: resource limitations, unavailability of materials, manufacturing complexities and ethical compliance issues; any approach that resolves all or some of these is of some interest. The aim of this study is applying the recently discovered concept of finite similitude as a novel approach for the design of scaled biomechanical experiments supported with analysis using a commercial finite-element package and validated by means of image correlation software. The study of isotropic scaling of synthetic bones leads to the selection of three-dimensional (3D) printed materials for the trial-space materials. These materials conforming to the theory are analysed in finite-element models of a cylinder and femur geometries undergoing compression, tension, torsion and bending tests to assess the efficacy of the approach using reverse scaling of the approach. The finite-element results show similar strain patterns in the surface for the cylinder with a maximum difference of less than 10% and for the femur with a maximum difference of less than 4% across all tests. Finally, the trial-space, physical-trial experimentation using 3D printed materials for compression and bending testing provides a good agreement in a Bland–Altman statistical analysis, providing good supporting evidence for the practicality of the approach.

Global Characterization of Failure Modes Under Impact Loading in Structural Components Made of Low Ductility Materials

2001 ◽  
Author(s):  
Shen Rong Wu ◽  
Xiaoming Chen ◽  
Weiran Hu
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Failure Process ◽  
Failure Criteria ◽  
Tensile Failure ◽  
Forming Limit ◽  
Structural Components ◽  
Explicit Finite Element ◽  
Finite Element Software ◽  
The Impact

Abstract This study reviews the impact failure modes of structural components made of materials with low ductility such as aluminum and magnesium. Tensile failure is observed at large stretch area or on the tension side of large bending deformation. Material breakage due to shear may also occur. There are several approaches to simulate the material failure process in explicit finite element software used for crashworthiness analysis. Evaluation of the effective applications of these material models is presented with a finite element simulation of bi-axial loading tests. The forming limit diagram is used to evaluate various failure criteria. Component crash simulations are presented to demonstrate the applications of failure criteria.

scholarly journals Dynamic tensile properties, deformation, and failure testing of impact-loaded coal samples with various water content

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhen Wei ◽  
Ke Yang ◽  
Xiao-Lou Chi ◽  
Xiang He ◽  
Xin-Yuan Zhao ◽  
...  
Keyword(s):  
Water Content ◽  
Coal Sample ◽  
Failure Process ◽  
Strain Curve ◽  
Peak Stress ◽  
Test System ◽  
Image Correlation ◽  
Tensile Failure ◽  
Peak Strain ◽  
Rate Correlation

AbstractDisc coal samples with different water content were tested using the split Hopkinson press bar test system. Their dynamic tensile failure process was monitored via an ultra-high-speed digital image correlation system. The deformation trend and failure characteristics as a function of the water content were analyzed, and the water content effect on dynamic mechanical properties was investigated. The results demonstrated that the dynamic stress–strain curve of the coal samples consisted of four stages. As the water content increased, the coal sample brittleness degraded, while its ductility was enhanced. Quadratic polynomial functions can describe dynamic peak stress, peak strain, and loading pressure. Under different loading pressures, the dynamic peak stress exhibited a concave bending trend as the water content increased. The coal sample's dynamic tensile strength had a strong rate correlation, and the saturated coal sample exhibited the highest rate correlation. Under high-rate loading, the inertia effect and the Stefan effect of water in coal samples hinder the initiation and propagation of coal sample cracks, improving the coal sample's strength. The research results provide a basic theoretical basis for the prevention and control of rock burst in coal mines.

Tensile strength of 3D printed materials: Review and reassessment of test parameters

2018 ◽  
Vol 60 (7-8) ◽  
pp. 679-686 ◽  
Author(s):  
Jim Floor ◽  
Bas van Deursen ◽  
Erik Tempelman
Keyword(s):  
Tensile Strength ◽  
Test Parameters ◽  
3D Printed ◽  
Printed Materials

scholarly journals A Novel Approach for a Faster Prototyping of Winter Sport Equipment Using Digital Image Correlation and 3D Printing

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 125
Author(s):  
Martino Colonna ◽  
Benno Zingerle ◽  
Maria Federica Parisi ◽  
Claudio Gioia ◽  
Alessandro Speranzoni ◽  
...  
Keyword(s):  
3D Printing ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Sport Activity ◽  
Image Correlation ◽  
Topological Optimization ◽  
Design Parameters ◽  
Sport Equipment ◽  
Novel Approach ◽  
3D Printed

The optimization of sport equipment parts requires considerable time and high costs due to the high complexity of the development process. For this reason, we have developed a novel approach to decrease the cost and time for the optimization of the design, which consists of producing a first prototype by 3D printing, applying the forces that normally acts during the sport activity using a test bench, and then measuring the local deformations using 3D digital image correlation (DIC). The design parameters are then modified by topological optimization and then DIC is performed again on the new 3D-printed modified part. The DIC analysis of 3D-printed parts has shown a good agreement with that of the injection-molded ones. The deformation measured with DIC are also well correlated with those provided by finite element method (FEM) analysis, and therefore DIC analysis proves to be a powerful tool to validate FEM models.

NMR magnets for portable applications using 3D printed materials

2021 ◽  
pp. 106934
Author(s):  
Belal M.K. Alnajjar ◽  
André Buchau ◽  
Lars Baumgártner ◽  
Jens Anders
Keyword(s):  
3D Printed ◽  
Printed Materials

scholarly journals Stress–strain relationship model of glulam bamboo under axial loading

2020 ◽  
Vol 29 ◽  
pp. 2633366X2095872
Author(s):  
Yang Wei ◽  
Mengqian Zhou ◽  
Kunpeng Zhao ◽  
Kang Zhao ◽  
Guofen Li
Keyword(s):  
Tensile Stress ◽  
Compressive Stress ◽  
Failure Modes ◽  
Axial Loading ◽  
Tensile Failure ◽  
Stress Strain ◽  
Laminated Bamboo ◽  
Bamboo Scrimber ◽  
Strain Relationship ◽  
Strain Model

Glulam bamboo has been preliminarily explored for use as a structural building material, and its stress–strain model under axial loading has a fundamental role in the analysis of bamboo components. To study the tension and compression behaviour of glulam bamboo, the bamboo scrimber and laminated bamboo as two kinds of typical glulam bamboo materials were tested under axial loading. Their mechanical behaviour and failure modes were investigated. The results showed that the bamboo scrimber and laminated bamboo have similar failure modes. For tensile failure, bamboo fibres were ruptured with sawtooth failure surfaces shown as brittle failure; for compression failure, the two modes of compression are buckling and compression shear failure. The stress–strain relationship curves of the bamboo scrimber and laminated bamboo are also similar. The tensile stress–strain curves showed a linear relationship, and the compressive stress–strain curves can be divided into three stages: elastic, elastoplastic and post-yield. Based on the test results, the stress–strain model was proposed for glulam bamboo, in which a linear equation was used to describe the tensile stress–strain relationship and the Richard–Abbott model was employed to model the compressive stress–strain relationship. A comparison with the experimental results shows that the predicted results are in good agreement with the experimental curves.

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