scholarly journals Strain Field Evolution Characteristics of Free Surface during Crater Blasting in Sandstone under High Stress

2020 ◽  
Vol 10 (18) ◽  
pp. 6285 ◽  
Author(s):  
Fengpeng Zhang ◽  
Guangliang Yan ◽  
Qibo Yang ◽  
Jikai Gao ◽  
Yuanhui Li
Keyword(s):  
Free Surface ◽  
Static Loading ◽  
Strain Field ◽  
Tensile Strain ◽  
High Stress ◽  
Principal Strain ◽  
Rock Blasting ◽  
Tensile Cracks ◽  
Field Evolution ◽  
Maximum Principal Strain

Considering the problems related to hard rock blasting under high in-situ stresses at large depths, we conducted crater blasting tests on sandstone specimens under three static load conditions to investigate the strain field evolution of rock blasting under high stress. The digital image correlation (DIC) technique was used to monitor the evolution of the strain field on the free surface. Thus, the influence of the static stress on the blasting strain field was analyzed, and the formation mechanism of cracks on the free surface was elucidated. The results indicate that a circular tensile strain zone was formed without static loading. The direction of the maximum principal strain was perpendicular to the radius, which lead to the random emergence of multiple radial tensile cracks. Under a uniaxial static loading, an elliptical tensile strain zone was formed. The direction of the maximum principal strain was perpendicular to the static loading direction. This facilitated the initiation and propagation of tensile cracks preferentially in the direction parallel to the static loading. Under an equal biaxial static loading, the initial compressive strain in the specimen reduced the increment rate of the blasting strain, and restrained the formation of surface cracks. Besides, a determination method for dynamic tensile fracture strain of rock was proposed.

Roughening and strain-field evolution at a grain boundary in α−Al2O3

2018 ◽  
Vol 2 (11) ◽  
Author(s):  
Sung Bo Lee ◽  
Seung-Yong Lee ◽  
Seung Jo Yoo ◽  
Yoonkoo Kim ◽  
Jin-Gyu Kim ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Strain Field ◽  
Field Evolution ◽  
Α Al2o3

Impact of Three-Dimensional Maximum Principal Strain Using Cardiac Computed Tomography in Aortic Stenosis

2017 ◽  
Vol 23 (10) ◽  
pp. S80
Author(s):  
Moeko Suzuki ◽  
Teruyoshi Uetani ◽  
Jun Aono ◽  
Takayuki Nagai ◽  
Kazuhisa Nishimura ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Aortic Stenosis ◽  
Cardiac Computed Tomography ◽  
Three Dimensional ◽  
Principal Strain ◽  
Maximum Principal Strain

Maximum Principal Strain Correlates with Spinal Cord Tissue Damage in Contusion and Dislocation Injuries in the Rat Cervical Spine

2012 ◽  
Vol 29 (8) ◽  
pp. 1574-1585 ◽  
Author(s):  
Colin M. Russell ◽  
Anthony M. Choo ◽  
Wolfram Tetzlaff ◽  
Tae-Eun Chung ◽  
Thomas R. Oxland
Keyword(s):  
Spinal Cord ◽  
Cervical Spine ◽  
Tissue Damage ◽  
Principal Strain ◽  
Spinal Cord Tissue ◽  
Maximum Principal Strain

The Influence of Neck Stiffness on Head Kinematics and Maximum Principal Strain Associated With Youth American Football Collisions

2021 ◽  
pp. 1-8
Author(s):  
Janie Cournoyer ◽  
David Koncan ◽  
Michael D. Gilchrist ◽  
T. Blaine Hoshizaki
Keyword(s):  
American Football ◽  
Principal Strain ◽  
Neck Stiffness ◽  
Head Impacts ◽  
Head Kinematics ◽  
Upper Trapezius ◽  
Maximum Principal Strain ◽  
Direct Head ◽  
Hybrid Iii ◽  
Neck Strength

Understanding the relationship between head mass and neck stiffness during direct head impacts is especially concerning in youth sports where athletes have higher proportional head mass to neck strength. This study compared 2 neck stiffness conditions for peak linear and rotational acceleration and brain tissue deformations across 3 impact velocities, 3 impact locations, and 2 striking masses. A pendulum fitted with a nylon cap was used to impact a fifth percentile hybrid III headform equipped with 9 accelerometers and fitted with a youth American football helmet. The 2 neck stiffness conditions consisted of a neckform with and without resistance in 3 planes, representing the upper trapezius, the splenius capitis, and the sternocleidomastoid muscles. Increased neck stiffness resulted in significant changes in head kinematics and maximum principal strain specific to impact velocity, impact location, and striking mass.

scholarly journals Strain field evolution at the ductile-to-brittle transition: a case study on ice

Solid Earth ◽  
2017 ◽  
Vol 8 (5) ◽  
pp. 943-953 ◽  
Author(s):  
Thomas Chauve ◽  
Maurine Montagnat ◽  
Cedric Lachaud ◽  
David Georges ◽  
Pierre Vacher
Keyword(s):  
Stress Concentration ◽  
Dynamic Recrystallization ◽  
Strain Field ◽  
Crack Opening ◽  
Local Stress ◽  
Image Correlation ◽  
Brittle Transition ◽  
Field Evolution ◽  
Crack Tips ◽  
Ductile To Brittle Transition

Abstract. This paper presents, for the first time, the evolution of the local heterogeneous strain field around intra-granular cracking in polycrystalline ice, at the onset of tertiary creep. Owing to the high homologous temperature conditions and relatively low compressive stress applied, stress concentration at the crack tips is relaxed by plastic mechanisms associated with dynamic recrystallization. Strain field evolution followed by digital image correlation (DIC) directly shows the redistribution of strain during crack opening, but also the redistribution driven by crack tip plasticity mechanisms and recrystallization. Associated local changes in microstructure induce modifications of the local stress field evidenced by crack closure during deformation. At the ductile-to-brittle transition in ice, micro-cracking and dynamic recrystallization mechanisms can co-exist and interact, the later being efficient to relax stress concentration at the crack tips.

scholarly journals Direct measurement of strain field evolution during dynamic deformation of an energetic material

1998 ◽  
Author(s):  
B. W. Asay ◽  
B. F. Henson ◽  
P. M. Dickson ◽  
C. S. Fugard ◽  
D. J. Funk
Keyword(s):  
Direct Measurement ◽  
Strain Field ◽  
Dynamic Deformation ◽  
Energetic Material ◽  
Field Evolution

The influence of impact force redistribution and redirection on maximum principal strain for helmeted head impacts

2019 ◽  
Vol 22 (13) ◽  
pp. 1047-1060 ◽  
Author(s):  
Karen Taylor ◽  
T. Blaine Hoshizaki ◽  
Michael Gilchrist
Keyword(s):  
Impact Force ◽  
Principal Strain ◽  
Head Impacts ◽  
Maximum Principal Strain

Collagen Fiber Alignment and Maximum Principal Strain in the Glenohumeral Capsule Predict Location of Failure During Uniaxial Extension

2011 ◽  
Author(s):  
Kelvin Luu ◽  
Carrie A. Voycheck ◽  
Patrick J. McMahon ◽  
Richard E. Debski
Keyword(s):  
Collagen Fiber ◽  
Glenohumeral Joint ◽  
Uniaxial Extension ◽  
Principal Strain ◽  
Fiber Alignment ◽  
Glenohumeral Ligament ◽  
Maximum Principal Strain ◽  
Inferior Glenohumeral Ligament ◽  
Glenohumeral Capsule ◽  
Collagen Fiber Alignment

The glenohumeral joint is frequently dislocated causing injury to the glenohumeral capsule (axillary pouch (AP), anterior band of the inferior glenohumeral ligament (AB-IGHL), posterior band of the inferior glenohumeral ligament (PB-IGHL), posterior (Post), and anterosuperior region (AS)). [1, 2] The capsule is a passive stabilizer to the glenohumeral joint and primarily functions to resist dislocation during extreme ranges of motion. [3] When unloaded, the capsule consists of randomly oriented collagen fibers, which play a pertinent role in its function to resist loading in multiple directions. [4] The location of failure in only the axillary pouch has been shown to correspond with the highest degree of collagen fiber orientation and maximum principle strain just prior to failure. [4, 5] However, several discrepancies were found when comparing the collagen fiber alignment between the AB-IGHL, AP, and PB-IGHL. [3,6,7] Therefore, the objective was to determine the collagen fiber alignment and maximum principal strain in five regions of the capsule during uniaxial extension to failure and to determine if these parameters could predict the location of tissue failure. Since the capsule functions as a continuous sheet, we hypothesized that maximum principal strain and peak collagen fiber alignment would correspond with the location of tissue failure in all regions of the glenohumeral capsule.

Stress Re-Distribution Induced by Creep Relaxation Around a Notch Loaded in Tension: Measurement and Modeling

2009 ◽  
Author(s):  
Brian W. Leitch ◽  
Nicolas Christodoulou ◽  
Ronald Rogge
Keyword(s):  
Heavy Water ◽  
Strain Field ◽  
High Stress ◽  
Natural Uranium ◽  
Thermal Creep ◽  
Three Dimensions ◽  
Pressure Tube ◽  
Primary Coolant ◽  
Fuel Channel ◽  
Creep Response

The majority of the pressure-retaining components in the core of a CANDU power generation system are manufactured from zirconium. The horizontal fuel channel components and the fuel bundles that contain the natural uranium fuel are manufactured using various grades of zirconium. The fuel channel consists of two concentric tubes; an internally pressurized tube (Zr-2.5%Nb) that contains the fuel bundles (Zr-4) and the re-circulating heavy-water primary coolant, enclosed by a larger diameter calandria tube (Zircaloy) that separates the pressure tube from the heavy-water moderator. Re-fuelling and other fuel management operations can create surface defects in the tubes and fuel bundle sheathing. Stress analyses of these small notches may indicate that, under certain conditions, cracks can be formed at the root of these notches. These flaws are locations of stress concentration in the internally pressurized tube and can initiate a failure mechanism known as Delayed Hydride Cracking. The anisotropic material properties of these zirconium components adds an additional level of complexity in an analysis. However, the occurrences of these life-limiting events appear to be minimized mainly due to beneficial contributors such as stress relaxation around the scratches. One of the most likely reasons for this relaxation is thermal creep. Previously [1], the measurement and modeling of thermal creep relaxation under constant displacement was examined using 2-D finite element (FE) models. This paper extends both the measurement and modeling of the relaxing stress/strain field to the more demanding boundary condition of constant applied load. Neutron diffraction is used to determine the changing strain field around a single notched, axially orientated specimen loaded in tension. This specimen orientation and loading configuration is modeled in three dimensions using a hybrid explicit FE program [2] that contains materials subroutines that describe high stress creep specially developed to simulate the highly anisotropic creep response of pressure tube materials. Despite the difficulty of obtaining precise delineation of the moving strain field, a good agreement between the measurements and the 3-D FE creep results is achieved. Using the creep subroutines, the FE models are used to examine the creep response of a single notched, transversely orientated specimen loaded in tension in the hoop direction.

scholarly journals Strain Analysis of the Nuozhadu High Rockfill Dam during Initial Impoundment

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Xiaolong Lv ◽  
Shichun Chi
Keyword(s):  
Shear Strain ◽  
Strain Field ◽  
Tensile Strain ◽  
Strain Analysis ◽  
Smoothing Method ◽  
Regulatory Agencies ◽  
Strain Concentration ◽  
Rockfill Dam ◽  
High Rockfill Dam

The safety of rockfill dams during initial impoundment has always been an issue of interest for regulatory agencies. Specifically, it is necessary to identify potential tensile strain zones and shear strain concentration zones in which cracks may form. In this paper, a meshless smoothing method is proposed to construct the strain field of a prototype dam based on monitoring displacement data. For verification, this method is applied to calculate the strain field of the Nuozhadu core wall rockfill dam. The results show that the proposed method can provide regulatory agencies with an effective tool for dam inspection during initial impoundment.

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