scholarly journals A modelling resin material and its application in rock-failure study: Samples with two 3D internal fracture surfaces

2020 ◽  
Vol 12 (1) ◽  
pp. 1237-1246
Author(s):  
Jinwei Fu ◽  
Shuli Liu ◽  
Lielie Li ◽  
Jianzhou Wang
Keyword(s):  
Rock Failure ◽  
Wing Crack ◽  
Processing Technologies ◽  
Fracture Surfaces ◽  
Failure Evolution ◽  
Similar Materials ◽  
Strain Relationship ◽  
Secondary Fractures ◽  
Materials Used ◽  
Internal Fracture

AbstractThe mechanism of fracture propagation, interaction and coalescence inside rock masses is a highly concerned issue in geotechnical engineering. But as it is difficult to manufacture 3D internal pre-fractures and observe directly the failure evolution process inside real rocks or their opaque similar materials, most previous studies have been limited to 2D conditions. The experiment investigation on 3D rock failure is still in a preliminary stage. In this study, a resin material has been developed by extensive formula tries. It is absolutely transparent and the ratio of tension–compression strength (brittleness value) can be 1/6.6 at −10 to −15℃. It is much more brittle and rock-like than analogous materials used by former scholars. A set of preparation, casting mould, and post-processing technologies were established and specimen-making with multiple pre-fractures is enabled. In the designed scheme, specimens are made with two parallel internal fracture surfaces yet of four different stagger separations. Uniaxial tests were carried out and the stress–strain relationship is analysed. It is shown that the specimen has gone through four stages as the traditional rock test before failure. Many diverse forms of secondary fractures, such as wrapping wing crack, petaloid crack, and giant quasi-wrapping fracture surface, which were not found in 2D conditions have appeared and their evolutions were clearly seen in each stage.

scholarly journals Investigation of Failure in Gas Turbines: Part 2 — Engineering and Metallographic Aspects of Failure Investigation

1993 ◽  
Author(s):  
Robert E. Dundas
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Heavy Duty ◽  
Metallographic Examination ◽  
Fracture Surfaces ◽  
Failure Investigation ◽  
Materials Used ◽  
Component Failures

This paper opens with a discussion of the various mechanisms of cracking and fracture encountered in gas turbine failures, and discusses the use of metallographic examination of crack and fracture surfaces. The various types of materials used in the major components of heavy-duty industrial and aeroderivative gas turbines are tabulated. A collection of macroscopic and microscopic fractographs of the various mechanisms of failure in gas turbine components is then presented for reference in failure investigation. A discussion of compressor damage due to surge, as well as some overall observations on component failures, follows. Finally, a listing of the most likely types of failure of the various major components is given.

Use Wear on Bone and Antler Tools from the Mackenzie Delta, Northwest Territories

1994 ◽  
Vol 59 (2) ◽  
pp. 316-334 ◽  
Author(s):  
Genevieve M. LeMoine
Keyword(s):  
Northwest Territories ◽  
Experimental Results ◽  
Fish Scales ◽  
Mackenzie Delta ◽  
Use Wear ◽  
Similar Materials ◽  
Series Of Experiments ◽  
Materials Used ◽  
Historical Accounts ◽  
Lines Of Evidence

A series of experiments making and using bone and antler tools show that functional identifications of these tools can be made with confidence in some circumstances. Using principles from the field of tribology, the experiments demonstrate that different uses leave different microscopic traces on bone and antler. They also show that when the materials used are similar, the wear produced will be similar. In particular, wet materials, including snow, ice, wet hide, and wet antler all produce nearly identical microscopic patterns. Other groups of similar materials, such as bone, antler, and wood, or fish scales and hair, present the same problem. Although differences can be detected, these may not be preserved on archaeological tool specimens. Application of the experimental results to bone and antler tools from the Mackenzie Delta illustrates that functional identifications of tools can be made with confidence, despite the problem of similar microscopic patterns, when other lines of evidence (ethnographic and historical accounts, distribution of wear) are taken into account. When such information is lacking, functional identifications are more difficult and must be made with more caution.

scholarly journals Special Issue: Mechanical Properties in Progressive Mechanically Processed Metallic Materials

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4668
Author(s):  
Radim Kocich ◽  
Lenka Kunčická
Keyword(s):  
Mechanical Properties ◽  
Physical Parameters ◽  
Metallic Materials ◽  
Special Issue ◽  
Processing Technologies ◽  
Recent Developments ◽  
Metallic Composites ◽  
Materials Used ◽  
High Level ◽  
Alloys And Compounds

The research and development of modern metallic materials imparts not only the introduction of innovative alloys and compounds, but also the increasing lifetime of existing materials via optimized deformation processing. Among the essential features of progressive metallic materials used for modern applications are enhanced mechanical properties, but also other high-level functional characteristics, such as thermal–physical parameters, corrosion rate, and electric resistance. The properties of materials and alloys ensue from their structures, which can primarily be affected by the preparation/production process. The Special Issue “Mechanical Properties in Progressive Mechanically Processed Metallic Materials” was established to present recent developments and innovations particularly in the engineering field. The Special Issue comprises papers dealing with modern materials, such as metallic composites and pseudoalloys, as well as developments in various processing technologies.

Physical Properties of Porous Clay Ceramic-Ware

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
A. K. Plappally ◽  
I. Yakub ◽  
L. C. Brown ◽  
W. O. Soboyejo ◽  
A. B. O. Soboyejo
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
Raw Materials ◽  
Ceramic Materials ◽  
Ceramic Ware ◽  
Strength Development ◽  
Similar Materials ◽  
Ceramic Manufacture ◽  
Materials Used ◽  
Clay Ceramics

The focus of this study is on the physical properties of clay ceramic materials compatible for drinking water filtration. A multiparameter lognormal multivariate regression approach is proposed for assessing the combined effects of quantity of compositional constituent of raw materials used in ceramic manufacture on toughness. The approach was validated for two specimen types (T- and S-specimens) derived from a circular base of the frustum shaped, porous clay ceramic ware (PCCW). The PCCW were manufactured from clay and sieved sawdust mixed at distinct volume fractions. The variation of the porosity and density of the PCCW was studied with respect to the amounts of sawdust and clay used in the manufacturing. The research helped to clearly define the roles of clay and sawdust quantities for strength development in both T- and S-specimen. A generalized experimental approach is proposed for estimation of mechanical properties of clay ceramics as a function of the material constituent fractions. A polynomial relationship was developed between the compressive strength and density of the PCCW material. The statistical model expressions developed herein may be used for the prediction of material and mechanical properties of similar materials, including natural and engineered materials.

Stress–Energy Mechanism for Rock Failure Evolution Based on Damage Mechanics in Hard Rock

2019 ◽  
Vol 53 (3) ◽  
pp. 1021-1037 ◽  
Author(s):  
Chunlai Wang ◽  
Binbin He ◽  
Xiaolin Hou ◽  
Jieyu Li ◽  
Lu Liu
Keyword(s):  
Damage Mechanics ◽  
Hard Rock ◽  
Rock Failure ◽  
Energy Mechanism ◽  
Failure Evolution ◽  
Stress Energy

Behavior of Fiberglass Polymer Composites under Ballistic Impact and Quasi-Static Punch Shear Tests

2016 ◽  
Vol 881 ◽  
pp. 300-306 ◽  
Author(s):  
Agnys Jony Gomes Fernandes ◽  
Wanderley Ferreira de Amorim Jr. ◽  
Walter Belarmino Filho ◽  
Isac Paiva Guedes ◽  
Andréa Lopes Silva ◽  
...  
Keyword(s):  
Polymer Composites ◽  
Polyester Resin ◽  
Ballistic Impact ◽  
Woven Fabric ◽  
Shear Tests ◽  
Ballistic Performance ◽  
Displacement Behavior ◽  
Chopped Strand Mat ◽  
Materials Used ◽  
Internal Fracture

In the last decades, the composite materials were used in the modern ballistic armor systems. Thus, techniques have been developed to predict its mechanical properties, damage mechanisms and strength associated to ballistic impact penetration. The objective of this work was the ballistic impact and quasi-static punch shear behavior of fiberglass polymer composites. The materials used in the experiments were: woven fabric and chopped strand mat E-glass fiber and polyester resin. The composites submitted to ballistic impact and quasi-static punch shear tests had 1, 5, 10, 15, and 20 layers and 5, 8, 10, 12, 14, 15, and 20 layers, respectively. A quasi-static punch shear fixture test was developed. The best ballistic performance composite was the 10 layers woven fabric. In quasi-static punch shear test, it was possible to analyze the internal fracture of composites, and the load x displacement behavior was observed.

scholarly journals The Use of Formal Knowledge Representation in Operating on Resources Concerning Cast Iron Processing

2015 ◽  
Vol 15 (2) ◽  
pp. 39-42
Author(s):  
S. Kluska-Nawarecka ◽  
D. Wilk-Kołodziejczyk ◽  
G. Rojek ◽  
K. Regulski ◽  
G. Polek
Keyword(s):  
Cast Iron ◽  
Knowledge Representation ◽  
Formal Representation ◽  
Formal Knowledge ◽  
External Data ◽  
Similar Materials ◽  
Specific Material ◽  
Materials Used ◽  
Processing Techniques ◽  
To Receive

Abstract The problem of materials selection in terms of their mechanical properties during the design of new products is a key issue of design. The complexity of this process is mainly due to a multitude of variants in the previously produced materials and the possibility of their further processing improving the properties. In everyday practice, the problem is solved basing on expert or designer knowledge. The paper is the proposition of a solution using computer-aided analysis of material experimental data, which may be acquired from external data sources. In both cases, taking into account the rapid growth of data, additional tools become increasingly important, mainly those which offer support for adding, viewing, and simple comparison of different experiments. In this paper, the use of formal knowledge representation in the form of an ontology is proposed as a bridge between physical repositories of data in the form of files and user queries, which are usually formulated in natural language. The number and the sophisticated internal structure of attributes or parameters that could be the criteria of the search for the user are an important issue in the traditional data search tools. Ontology, as a formal representation of knowledge, enables taking into account the known relationships between concepts in the field of cast iron, materials used and processing techniques. This allows the user to receive support by searching the results of experiments that relate to a specific material or processing treatment. Automatic presentation of the results which relate to similar materials or similar processing treatments is also possible, which should make the conducted analysis of the selection of materials or processing treatments more comprehensive by including a wider range of possible solutions.

scholarly journals Some Comments on Designing of Steel Structures According to European Standards

2019 ◽  
Vol 18 (2) ◽  
pp. 113-120
Author(s):  
Y. Y. Davydov
Keyword(s):  
Steel Structures ◽  
Load Combination ◽  
Load Factors ◽  
Partial Load ◽  
Calculated Load ◽  
Similar Materials ◽  
Technical Specifications ◽  
The Republic ◽  
European Standards ◽  
Materials Used

Critical comments on the European standards for designing steel structures including welded and bolted joints have been given on the basis of application experience and executed analysis. Comments are presented in comparison with similar regulatory documents which are in effect in Belarus. European standards concerning loads (determination of calculated load values and drawing up of design load combination) have been also analyzed. Particular attention has been paid to the analysis of European standard requirements to steel and welding materials and their comparison with mechanical characteristics of similar materials used for manufacture of steel structures in Belarus. The paper gives notice to the rules which are accepted in the European norms and the rules being compared with the similar rules used in Construction rules and regulations (SNiP) lead to a significant increase in material consumption of steel structures. First of all, it concerns assignment of partial load factors and classification of sections for ensuring local stability of compressed and partially compressed elements. The paper pays a special notice to the rules of Eurocodes that do not meet requirements of State standards and technical specifications operating in the Republic of Belarus. Significant limitations of some European rules regarding calculation of centrally and eccentrically compressed elements, absence of rules for testing overall stability of through and step columns which are widely used while implementing projects Belarus have been described in the paper. Conclusions have been made on the basis of the analysis results and according to them application of European standards for designing steel structures has significant limitations on the territory of the Republic of Belarus.

scholarly journals Rare-earth metal ore processing technologies when developing new deposits

2020 ◽  
pp. 47-53
Author(s):  
T. I. Yushina ◽  
◽  
I. M. Petrov ◽  
S. A. Cherny ◽  
A. I. Petrova ◽  
...  
Keyword(s):  
Rare Earth ◽  
Raw Materials ◽  
Rare Earth Metals ◽  
Earth Metal ◽  
Dense Medium ◽  
Clear Trend ◽  
Processing Technologies ◽  
Hydrometallurgical Processing ◽  
Mass Fractions ◽  
Materials Used

The article provides a brief overview of processing technologies for rare-earth raw materials used under greenfield development projects in different countries of the world (Africa, Greenland, Australia, Canada). The projects feature deposits with different mineral compositions, mass fractions of rare-earth metals (REM) in ores of 0.2 to 15 %, and the presence of niobium, zirconium, tantalum, phosphorus, uranium, and thorium. The resulting production facilities will extract 180 kt to 7.2 Mt rare-earth ore annually to generate 1.5 to 20 kt oxides of heavy and light groups of rare-earth metals along with the rare metals. The analysis of technologies for the projects considered demonstrates that magnetic and radiometric separation, dense-medium concentration and flotation with hydrometallurgical processing in the form of leaching with sulfuric or hydrochloric acid, followed by extraction of the target products, will be used for the processing of rare-earth raw materials. A characteristic feature of a number of projects is, first of all, the direct hydrometallurgical processing of the feed. The concentration technologies for ores containing rare-earth metals also indicate a clear trend towards a more active use of high-intensity magnetic separation. The main products to be obtained with these technologies will include composite concentrates of oxides or carbonates of rare-earth metals. At the same time, the commissioning dates for the projects are being repeatedly postponed; the implementation of many projects remains uncertain, which is largely due to the stagnant dynamics of global prices for rare-earth metals.

Numerical Approach to Investigating Pre-Existed Cracks in Rocks

2005 ◽  
Vol 297-300 ◽  
pp. 2612-2616 ◽  
Author(s):  
Shu Hong Wang ◽  
Huo Ran Sun ◽  
Tao Xu ◽  
Tian Hong Yang ◽  
En'de Wang
Keyword(s):  
Process Analysis ◽  
Failure Process ◽  
Numerical Approach ◽  
Rock Failure ◽  
Natural Material ◽  
Failure Behavior ◽  
Typical Sample ◽  
Rock Failure Process ◽  
Similar Materials ◽  
Almost All

Rock failure analysis is an important research in investigating the behavior of rocks, especially its failure process. And a rock sample, which contains pre-existing cracks, is a typical sample to investigate the rock failure behavior which under tension or compression, because almost all the natural materials exist micro-flaws more or less. This mode is closed to the natural material character. By using Rock Failure Process Analysis code, RFPA2D, we present a numerical simulation and similar materials experiment on rock samples with two pre-existing cracks in uniaxial compression were conducted to investigate the initiation, propagation, coalescence of cracks and failure mechanism of rock. Numerical simulations visually reproduce the process of crack initiation, propagation and coalescence in rock, which are well tallied with experiments in laboratory.

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