scholarly journals Characterisation of buried blast loading

2020 ◽  
Vol 476 (2236) ◽  
pp. 20190791
Author(s):  
Sam Clarke ◽  
Sam Rigby ◽  
Steve Fay ◽  
Andrew Barr ◽  
Andy Tyas ◽  
...  
Keyword(s):  
Parametric Study ◽  
Load Transfer ◽  
Systematic Investigation ◽  
Surface Loading ◽  
Material Particle ◽  
Soil Material ◽  
Temporal Form ◽  
Load Distributions ◽  
Explosive Charges ◽  
Depth Of Burial

While it is well known that detonation of shallow-buried high explosive charges generally results in above-surface loading which is greatly amplified compared with the same detonation in air, uncertainty persists as to the mechanisms leading to this effect. The work presented in this paper is a systematic investigation into the mechanisms of load transfer in buried blast events. This paper details the results from a parametric study into the mechanisms and magnitudes of load transfer following a shallow-buried explosion, where spatial and temporal load distributions are directly measured on a rigid surface using an array of Hopkinson pressure bars. In particular, the investigation has looked at the influence of both geometrical confinement and geotechnical conditions on the loading. The parametric study was separated into four main threads: the influence of physical confinement; gravimetric moisture content; stand-off distance and depth of burial; and soil material/particle size distribution. This study allows a direct observation of the contributions of each of these distinct parameters, and in particular the ability to discern how each parameter influences the temporal form and spatial distribution of the loading.

scholarly journals Investigation of alternative mechanisms of aquifer-system compaction and land subsidence in Shanghai

2015 ◽  
Vol 372 ◽  
pp. 13-15 ◽  
Author(s):  
Y. Yuan ◽  
Y.-S. Xu ◽  
S.-L. Shen ◽  
N. Zhang
Keyword(s):  
Load Transfer ◽  
Internal Erosion ◽  
Coarse Grained ◽  
Traditional Theory ◽  
Groundwater Extraction ◽  
Surface Loading ◽  
Aquifer System ◽  
Fine Grained ◽  
Hydraulic Gradients ◽  
Initial Results

Abstract. Alternative subsidence mechanisms related to groundwater extration and surface loading of built infrastructure in Shanghai have been evaluated to explain continued subsidence despite the controlled reduction of groundwater extraction. The traditional theory of aquifer-system compaction embodied in the aquitard drainage model cannot fully explain this phenomenon. Two possible alternative mechanisms were studied previously: (i) surface loading attributed to urban construction; (ii) creep occuring in sandy deposits of aquifers. These mechanisms could not fully explain the observed subsidence. Two additional alternative mechanistic models are proposed that involve principles of load transfer considering the temporally and spatially redistributed stresses associated with groundwater extraction: (i) the Cosserat continuum mechanism, considering shear force on the permeable coarse-grained matrial in the aquifer due to hydraulic gradients in the aquifer; and (ii) internal erosion of fine-grained (clay and silt) particles within the aquifer. Initial results based on simulations incorporating Cosserat mechanics look promising.

Effect of Extrusion Parameters on Mechanical Properties of Al6061-Ni-P Coated SiC Composites

2013 ◽  
Author(s):  
Ramesh Chinnakurli Suryanarayana ◽  
Sikhakolli Ramakrishna ◽  
Ummar Khan Attaullah ◽  
Smitha Hanumantha Badnur ◽  
Kumar Saheb
Keyword(s):  
Mechanical Properties ◽  
Load Transfer ◽  
Hot Extrusion ◽  
Matrix Alloy ◽  
Extrusion Process ◽  
Systematic Investigation ◽  
Strength Properties ◽  
Industrial Applications ◽  
The Matrix ◽  
Sic Composites

Extrusion of metal matrix composites (MMCs) is a very challenging one where in the bond between the reinforcement and the matrix alloy is crucial in getting high quality extrusions for industrial applications. In recent years researchers are focusing on developing aluminium based composites with metallic coated reinforcement to achieve good interfacial bonds to ensure smooth load transfer from the matrix on to reinforcement. However no information is available as regards hot extrusion of metallic coated reinforced MMCs. In the light of the above, the present work focuses on a systematic investigation on effect of extrusion process parameters on mechanical properties of Al6061-Ni-P coated SiC composites. From the investigation, it is observed that hardness, yield and ultimate strength of Al2014-SiC (Both uncoated and Ni-P coated) composites are higher when compared with the matrix alloy for all the extrusion ratios studied (4:1,5:1,10:1,15.5:1) at a given extrusion temperature. However, the ductility of composites decreases with increase in extrusion ratios. Further, heat treatment has a significant effect on the studied mechanical properties. Increase in extrusion temperatures at a given extrusion ratio has resulted in decrease in hardness and strength properties of both matrix alloy and developed composites.

Load Transfer Along the Bone-Dental Implant Interface

2009 ◽  
Author(s):  
Samira Faegh ◽  
Sinan Müftü
Keyword(s):  
Dental Implants ◽  
Load Transfer ◽  
Surface Characteristics ◽  
Systematic Investigation ◽  
Long Term Results ◽  
Implant Design ◽  
Patient Specific ◽  
Success Rates ◽  
Bone Implant ◽  
Patient Specific Implants

Endosseous dental implants are used as prosthetic treatment alternatives for treating partial edentulism [1]. Excellent long term results and high success rates have been achieved using dental implants during the past decades. Further improvements in implant protocols will include immediate loading, patient specific implants, applications for patients with extreme bone loss and extreme biting habits such as bruxism. The implant designs available in the market vary in size, shape, materials and surface characteristics [2], and address some of these concerns. An important factor in the implant design is the load transfer from the implant to bone during occlusal loading.[2,3] Load transfer starts along the bone-implant interface, and is affected by the loading type, material properties of the implant and prosthesis, implant geometry, surface structure, quality and quantity of the surrounding bone, and nature of the bone-implant interface [4]. While many studies using the finite element method (FEM) have been carried out [2–5], a systematic investigation of the load transfer at the bone implant interface, and the effects of various parameters that make the implant contour is lacking. The goal of this paper is to investigate one aspect of this multivariable problem, namely the effect of external implant threads on the load transfer along the bone-implant interface.

Geotechnical capacity of hollow-bar micropiles in cohesive soils

2014 ◽  
Vol 51 (10) ◽  
pp. 1123-1138 ◽  
Author(s):  
Ahmed Yehia Abd Elaziz ◽  
M. Hesham El Naggar
Keyword(s):  
Parametric Study ◽  
Load Transfer ◽  
Ground Improvement ◽  
Field Tests ◽  
Element Model ◽  
Cohesive Soils ◽  
Silty Clay ◽  
Test Results ◽  
Axial Capacity ◽  
Load Transfer Mechanism

Hollow-bar micropile construction, also known as self-drilled, is becoming a popular option because it allows faster installation processes and ground improvement at the same time. This paper presents a field study and numerical investigation on the behaviour of single hollow-bar micropiles embedded in a stiff silty clay deposit. Four hollow-bar micropiles were installed using an air-flushing technique employing large drilling carbide bits. Five axial tests were conducted on the four micropiles, comprising three compression and two tension monotonic axial tests. The results of the field tests are presented and analyzed in terms of load–displacement curves. A two-dimensional axisymmetric finite element model (FEM) was created and calibrated using the field test results. The calibrated FEM was utilized to select an appropriate failure criterion for hollow-bar micropiles depending on the load-transfer mechanism of the micropiles. In addition, the model was employed to carry out a parametric study to investigate the effect of the installation methodology, hollow-bar micropile geometry, and shear strength of the surrounding soils on the micropile capacity. Based on the outcomes of the parametric study, an equation is proposed to estimate the axial capacity of hollow-bar micropiles in cohesive soils.

On a consistent rod theory for a linearized anisotropic elastic material II. Verification and parametric study

2021 ◽  
pp. 108128652110349
Author(s):  
Xiaoyi Chen ◽  
Hui-Hui Dai ◽  
Erick Pruchnicki
Keyword(s):  
Principal Stress ◽  
Parametric Study ◽  
Elastic Moduli ◽  
Twist Angle ◽  
Transversely Isotropic ◽  
Anisotropic Materials ◽  
Systematic Investigation ◽  
Rod Theory ◽  
Specific Loading ◽  
Axial Twist

We have derived a rod theory by an asymptotic reduction method for a straight and circular rod composed of linearized anisotropic material in part I of this series. In the current work, we first verify the derived rod theory through five benchmark Saint-Venant’s problems. Then, under a specific loading condition (line force at the lateral surface with two clamped ends), we apply the rod theory to conduct a parametric study of the effects of elastic moduli on the deformation of a rod composed of four types of anisotropic materials including cubic, transversely isotropic, orthotropic, and monoclinic materials. Analytical solutions for the displacement, axial twist angle, stress, and principal stress have been obtained and a systematic investigation of the effects of elastic moduli on these quantities is conducted, which is the main feature of this paper. It is found that these elastic moduli arise in a certain form and in a certain order in the solutions, which gives information about how to appropriately choose moduli to adjust the deformation. Among the four anisotropic materials, it turns out that the monoclinic material presents the most remarkable mechanical behavior owing to the existence of a coupling coefficient: it yields coupled leading-order rod equations, non-trivial axial twist angle, non-negligible transverse shear deformation, and a more adjustable principal stress along the axis.

Axial and Moment Carrying Capacity of Split Sleeve Grouted Connections for Repair of Tubular Members

2019 ◽  
Author(s):  
N. Vignesh Chellappan ◽  
S. Nallayarasu
Keyword(s):  
Numerical Simulation ◽  
Carrying Capacity ◽  
Parametric Study ◽  
Load Transfer ◽  
Element Model ◽  
Offshore Structures ◽  
Geometric Parameters ◽  
Axial Tension ◽  
Load Transfer Mechanism ◽  
Comprehensive Study

Abstract The tubular members damaged by ship impact or falling objects require repair and rehabilitation in offshore structures. The repair of damaged underwater tubular member using welding is hazardous and expensive and hence alternative connection methods such as grouted clamp techniques have been in use for many decades. The existing guideline on the design of grouted connections especially under axial tension and moment is very limited and requires further study. The load transfer mechanism of grouted clamps depends on various geometric parameters and bond between clamp and parent member. A comprehensive study on split sleeve grouted connection for load transfer between two parts of tubular members has been investigated and presented. Numerical simulation of split sleeve grouted connection has been carried out using finite element model of tubular member – sleeve through bond strength of grout. The numerical model has been validated using existing guidelines and further parametric study has been carried out. The parametric study includes geometric parameters such as diameter to wall thickness ratio of split sleeve, sleeve friction length, grout strength and grout shrinkage. The simulations have been carried out for combination of axial tension and moment loading.

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