scholarly journals Simulation of Mining-Induced Ground Damage Using Orthogonal Experiments to Determine Key Parameters of Super-Large Coalface: A Case Study in Shendong Coalfield in China

2020 ◽  
Vol 10 (7) ◽  
pp. 2258 ◽  
Author(s):  
Yinfei Cai ◽  
Xiaojing Li ◽  
Wu Xiao ◽  
Wenkai Zhang
Keyword(s):  
Orthogonal Design ◽  
Ground Surface ◽  
Simulation Models ◽  
High Strength ◽  
Orthogonal Experiments ◽  
Significant Damage ◽  
Mining Conditions ◽  
Damage Extent ◽  
Ground Damage

High-strength mining of super-large coalfaces in the Shendong coalfield causes significant damage to the ground surface. To study the key parameters of undermined coalfaces that affect ground damage, 25 numerical simulation models were designed using an orthogonal experimental method based on the geological and mining conditions of the Bulianta Mine. In the orthogonal design, four factors (the lengths in both the dip and strike directions, the thickness and the mining speed of the coalface) were considered, with five levels designed for each factor. The subsidence displacements and deformations caused by the excavation were then simulated and verified using field surveying data. A damage extent index (DEI) was introduced and used to assess the extent of global ground damage caused by each simulative excavation. Analysis of variance (ANOVA) method was then employed to determine the key parameters of the coalface that significantly influence the ground damage. It was found that the coalface dip length and thickness and the coalface thickness can be regarded as the key parameters for ground objects of building and timberland, respectively. This research provides theoretical and technical support for the coordinated exploitation of resources and environments in Shendong and other similar, ecologically fragile coalfields.

scholarly journals Design Optimization of Explosion-Resistant System Consisting of Steel Slab and CFRP Frame

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2589
Author(s):  
Jung J. Kim
Keyword(s):  
Hybrid System ◽  
Impact Load ◽  
Load Condition ◽  
High Strength ◽  
Dynamic Responses ◽  
Elastoplastic Behavior ◽  
Reinforced Polymer ◽  
Steel Slab ◽  
Strength Material

This study presents an explosion-resistant hybrid system containing a steel slab and a carbon fiber-reinforced polymer (CFRP) frame. CFRP, which is a high-strength material, acts as an impact reflection part. Steel slab, which is a high-ductility material, plays a role as an impact energy absorption part. Based on the elastoplastic behavior of steel, a numerical model is proposed to simulate the dynamic responses of the hybrid system under the air pressure from an explosion. Based on this, a case study is conducted to analyze and identify the optimal design of the proposed hybrid system, which is subjected to an impact load condition. The observations from the case study show the optimal thicknesses of 8.2 and 7 mm for a steel slab and a ϕ100 mm CFRP pipe for the hybrid system, respectively. In addition, the ability of the proposed hybrid system to resist an uncertain explosion is demonstrated in the case study based on the reliability methodology.

Damage Quantitative Investigation of Beam Structure Based on Changing Ratio of Modal Curvature

2011 ◽  
Vol 255-260 ◽  
pp. 654-658
Author(s):  
Ji Ping Ge
Keyword(s):  
Linear Increase ◽  
Beam Structure ◽  
Quantitative Investigation ◽  
Supporting System ◽  
Damage Recognition ◽  
Modal Curvature ◽  
Damage Extent ◽  
Extent Of Damage ◽  
The Relationship

The changing ratio of modal curvature is proposed for damage recognition, and its ability of damage localization and damage quantitative has been studied in this paper. For testing the effect of damage recognition, two research parameters, the different section rigidity and the scope of damages, are included. And changing rules of the index with structure rigidity, constraints, and structure supporting system have been studied at the same time. The numerical analysis results indicated: The relation of linear increase exists between the changing ratio of modal curvature and the extent of damage, the changing slope of the index is bigger with the increase of damage extent; The boundary condition and the structure supporting system will affect the value of index; In the view of one special structure, case study should be carried to establish the relationship between value of index and the extent of damage.

Use of DNVGL-RP-C203 for Determining the Fatigue Capacity of Connectors

2021 ◽  
Author(s):  
Anthony Muff ◽  
Anders Wormsen ◽  
Torfinn Hørte ◽  
Arne Fjeldstad ◽  
Per Osen ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Testing ◽  
Experimental Testing ◽  
High Strength ◽  
Element Model ◽  
Fatigue Analysis ◽  
Full Scale ◽  
The Finite Element Model

Abstract Guidance for determining a S-N based fatigue capacity (safe life design) for preloaded connectors is included in Section 5.4 of the 2019 edition of DNVGL-RP-C203 (C203-2019). This section includes guidance on the finite element model representation, finite element based fatigue analysis and determination of the connector design fatigue capacity by use of one of the following methods: Method 1 by FEA based fatigue analysis, Method 2 by FEA based fatigue analysis and experimental testing and Method 3 by full-scale connector fatigue testing. The FEA based fatigue analysis makes use of Appendix D.2 in C203-2019 (“S-N curves for high strength steel applications for subsea”). Practical use of Section 5.4 is illustrated with a case study of a fatigue tested wellhead profile connector segment test. Further developments of Section 5.4 of C203-2019 are proposed. This included acceptance criteria for use of a segment test to validate the FEA based fatigue analysis of a full-scale preloaded connector.

Seismic solutions utilizing existing in-mine infrastructure for mineral exploration: A case study from Maseve platinum mine, South Africa

2022 ◽  
Vol 41 (1) ◽  
pp. 54-61
Author(s):  
Moyagabo K. Rapetsoa ◽  
Musa S. D. Manzi ◽  
Mpofana Sihoyiya ◽  
Michael Westgate ◽  
Phumlani Kubeka ◽  
...  
Keyword(s):  
South Africa ◽  
Seismic Data ◽  
Mineral Exploration ◽  
Ground Surface ◽  
Seismic Survey ◽  
Noisy Environment ◽  
Borehole Data ◽  
Passive Seismic ◽  
Below Ground

We demonstrate the application of seismic methods using in-mine infrastructure such as exploration tunnels to image platinum deposits and geologic structures using different acquisition configurations. In 2020, seismic experiments were conducted underground at the Maseve platinum mine in the Bushveld Complex of South Africa. These seismic experiments were part of the Advanced Orebody Knowledge project titled “Developing technologies that will be used to obtain information ahead of the mine face.” In these experiments, we recorded active and passive seismic data using surface nodal arrays and an in-mine seismic land streamer. We focus on analyzing only the in-mine active seismic portion of the survey. The tunnel seismic survey consisted of seven 2D profiles in exploration tunnels, located approximately 550 m below ground surface and a few meters above known platinum deposits. A careful data-processing approach was adopted to enhance high-quality reflections and suppress infrastructure-generated noise. Despite challenges presented by the in-mine noisy environment, we successfully imaged the platinum deposits with the aid of borehole data and geologic models. The results open opportunities to adapt surface-based geophysical instruments to address challenging in-mine environments for mineral exploration.

Development of a Design for Additive Manufacturing Worksheet for Medical Casts

2021 ◽  
Author(s):  
Heena Noh ◽  
Kijung Park ◽  
Kiwon Park ◽  
Gül E. Okudan Kremer
Keyword(s):  
Additive Manufacturing ◽  
High Strength ◽  
Design Guidelines ◽  
Operational Performance ◽  
Design For Additive Manufacturing ◽  
Trade Offs ◽  
Novice Designers ◽  
Criteria Importance ◽  
Design For Am

Abstract Traditional plaster casts often cause dermatitis due to disadvantages in usability and wearability. Additive manufacturing (AM) can fabricate customized casts to have light-weight, high strength, and better air permeability. Although existing studies have provided design for additive manufacturing (DfAM) guidelines to facilitate design applications for AM, most relevant studies focused on the mechanical properties of outputs and too general/specific design guidelines; novice designers may still have difficulty understanding trade-offs between functional and operational performance of various DfAM aspects for medical casts. As a response, this study proposes a DfAM worksheet for medical casts to effectively guide novice designers. First, important DfAM criteria and their possible solutions for medical casts are examined through a literature review to construct a basic DfAM framework for medical casts. Next, a scoring system that considers relative criteria importance and criteria evaluation from both functional and operational perspectives is developed to identify the overall suitability of a medical cast design for AM. A case study of finger cast designs was performed to identify the DfAM performance of the sample designs along with redesign requirements suggested by the worksheet. The proposed worksheet would be used to achieve rapid medical cast design by objectively assessing its suitability for AM.

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