Surface hardness as a proxy for weathering behaviour of limestone heritage: a case study on dated headstones on the Isle of Portland, UK

2016 ◽  
Vol 75 (10) ◽  
Author(s):  
K. Wilhelm ◽  
H. Viles ◽  
O. Burke ◽  
J. Mayaud
Keyword(s):  
Surface Hardness ◽  
Weathering Behaviour

Failure Analysis of Commercial Vehicle Crankshaft: A Case Study

2012 ◽  
Vol 192 ◽  
pp. 78-82 ◽  
Author(s):  
Shu Zhan Bai ◽  
Yu Ping Hu ◽  
Hai Long Zhang ◽  
Sheng Wei Zhou ◽  
Ying Jun Jia ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Bending Strength ◽  
Commercial Vehicle ◽  
Surface Hardness ◽  
Induction Hardening ◽  
Material Surface ◽  
Chemical Compositions ◽  
Metallic Inclusions ◽  
Mechanism Of Failure

A failure analysis has been conducted on a diesel engine crankshaft used in a commercial vehicle, which is made from 42CrMo forging steel, and the crankshaft was after induction hardening process. The fracture occurred between the 4th journal and the 4th crankpin, fracture section indicates that fatigue is the dominant mechanism of failure for this crankshaft. In order to find the failure causes, the dimension of journal boss fillet, material chemical compositions, surface hardness and depth of hardness layer were evaluated. Chemical compositions of crankshaft material, surface hardness and the depth of hardness layer are within the specified range, however the dimension of journal boss fillet is less than specified, and the transition zone of hardness layer was found on the journal boss fillet. Heavy segregation and many non-metallic inclusions aggregate zones were found from metallographic, these would lead to the reduction of endurance bending strength. FEA analysis results suggest that the dimension of journal boss fillet have an important effect on the stress and stress amplitude of the crankshaft. So the disqualification machining and material property are the main causes for the crankshaft fatigue fracture.

CAD-CAM Assisted Design and Preparation of Biocompatible Sensors and Transducers with Variable Microstructure

2019 ◽  
Vol 826 ◽  
pp. 73-80
Author(s):  
Ranvir Singh ◽  
Rupinder Singh ◽  
J.S. Dureja ◽  
Narinder Singh ◽  
Ilenia Farina
Keyword(s):  
Surface Hardness ◽  
Dimensional Accuracy ◽  
Stir Casting ◽  
Matrix Composites ◽  
Weight Percentage ◽  
Good Surface ◽  
Aesthetic Sense ◽  
Cad Cam ◽  
Good Surface Finish

This paper highlights the detailed procedure for preparation of biocompatible sensors and transducers by CAD-CAM assisted investment casting (IC). Along with the properties such as biocompatibility and bioactivity, the presented materials possess good surface finish (required for aesthetic sense), acceptable dimensional accuracy (required for assembly purposes) and good surface hardness (required while chewing). In this paper efforts were made for improving surface hardness, finish, and dimensional accuracy of biocompatible materials by controlling composition/proportion of Ni and Cr in IC process. In this case study stir casting (SC) assisted Ni and Cr based metal matrix composites (MMC) has been prepared and composite prepared were poured in the investment mould. The result of study reveals that different material composition influenced the microstructure and the hardness of the MMC prepared. Further with change in weight percentage of Ni and Cr, different microstructures with particle clustering was observed. The employment of nickel and chromium composites for the fabrication of novel sensors and transducers is discussed.

Thermoelastic Crack Analysis in Functionally Graded Pipelines Conveying Natural Gas by an FEM

2018 ◽  
Vol 10 (04) ◽  
pp. 1850036 ◽  
Author(s):  
Mohamed A. Attia ◽  
Mohamed A. Eltaher ◽  
Ahmed Soliman ◽  
Alaa A. Abdelrahman ◽  
Amal E. Alshorbagy
Keyword(s):  
Natural Gas ◽  
Surface Hardness ◽  
Element Model ◽  
Functionally Graded ◽  
Coupled Analysis ◽  
Graded Materials ◽  
Steel Material ◽  
Pressurized Fluids ◽  
Present Case Study

Internal cracks are a serious problem in pipelines conveying unsteady pressurized fluids like natural gas. To investigate and overcome this problem, this paper is motivated to highlight and study the response of gas pipes made of functionally graded materials (FGM) instead of the traditional carbon steel material. FGM is proposed as a composite material because of its advantages of minimizing the stress variation in the pipe. Ceramic is applied because of its durability against corrosion and its surface hardness against erosion. FGM properties are radially graded and a finite element model is developed and implemented into ABAQUS package, including FORTRAN subroutines which are adapted for the present case study. Coupled plane strain thermoelastic analysis is used to investigate the stresses and the stress intensity factor (SIF) at various crack depths under the actual thermomechanical loads. Both coupled and uncoupled thermomechanical approaches are introduced and compared to reveal the necessity of the coupled analysis for accurate FGMs’ investigation. The different influences of unsteady thermal and mechanical loads on the crack propagation are discussed.

Sandstones from Gottingen: its use, weathering behaviour and consolidation approaches a case study from the Bartholomaus cemetery

2007 ◽  
Vol 158 (4) ◽  
pp. 957-984
Author(s):  
Tobias Kracke ◽  
Christian Müller ◽  
Stefanie Krinninger ◽  
Wanja Wedekind ◽  
Jörg Rüdrich ◽  
...  
Keyword(s):  
Weathering Behaviour

The Genesis and Internal Dynamics of El Salvador's People's Revolutionary Army, 1970–1976

2014 ◽  
Vol 38 (01) ◽  
pp. 102-129
Author(s):  
ALBERTO MARTÍN ÁLVAREZ ◽  
EUDALD CORTINA ORERO
Keyword(s):  
Latin America ◽  
El Salvador ◽  
Early Years ◽  
Left Wing ◽  
Internal Dynamics ◽  
Internal Coherence ◽  
The 1960S

AbstractUsing interviews with former militants and previously unpublished documents, this article traces the genesis and internal dynamics of the Ejército Revolucionario del Pueblo (People's Revolutionary Army, ERP) in El Salvador during the early years of its existence (1970–6). This period was marked by the inability of the ERP to maintain internal coherence or any consensus on revolutionary strategy, which led to a series of splits and internal fights over control of the organisation. The evidence marshalled in this case study sheds new light on the origins of the armed Salvadorean Left and thus contributes to a wider understanding of the processes of formation and internal dynamics of armed left-wing groups that emerged from the 1960s onwards in Latin America.

Culture and the plasticity of perception

2020 ◽  
Vol 43 ◽  
Author(s):  
Michael Lifshitz ◽  
T. M. Luhrmann
Keyword(s):  
Cultural Context ◽  
Sensory Experience ◽  
Cultural Learning ◽  
The World

Abstract Culture shapes our basic sensory experience of the world. This is particularly striking in the study of religion and psychosis, where we and others have shown that cultural context determines both the structure and content of hallucination-like events. The cultural shaping of hallucinations may provide a rich case-study for linking cultural learning with emerging prediction-based models of perception.

Dual systems for all: Higher-order, role-based relational reasoning as a uniquely derived feature of human cognition

2019 ◽  
Vol 42 ◽  
Author(s):  
Daniel J. Povinelli ◽  
Gabrielle C. Glorioso ◽  
Shannon L. Kuznar ◽  
Mateja Pavlic
Keyword(s):  
Temporal Reasoning ◽  
Higher Order ◽  
Important Case ◽  
Human Cognition ◽  
Relational Reasoning ◽  
Dual Systems ◽  
First Order ◽  
Reasoning System ◽  
Role Based

Abstract Hoerl and McCormack demonstrate that although animals possess a sophisticated temporal updating system, there is no evidence that they also possess a temporal reasoning system. This important case study is directly related to the broader claim that although animals are manifestly capable of first-order (perceptually-based) relational reasoning, they lack the capacity for higher-order, role-based relational reasoning. We argue this distinction applies to all domains of cognition.

Sociocultural memory development research drives new directions in gadgetry science

2019 ◽  
Vol 42 ◽  
Author(s):  
Penny Van Bergen ◽  
John Sutton
Keyword(s):  
Episodic Memory ◽  
Autobiographical Memory ◽  
Developmental Psychology ◽  
Cross Cultural ◽  
Memory Development ◽  
Development Research ◽  
Cultural Research ◽  
New Directions ◽  
Cross Cultural Research

Abstract Sociocultural developmental psychology can drive new directions in gadgetry science. We use autobiographical memory, a compound capacity incorporating episodic memory, as a case study. Autobiographical memory emerges late in development, supported by interactions with parents. Intervention research highlights the causal influence of these interactions, whereas cross-cultural research demonstrates culturally determined diversity. Different patterns of inheritance are discussed.

Construction of plastic contact deformation maps on ceramics: a case study on aluminum nitride

1996 ◽  
Vol 54 ◽  
pp. 636-637
Author(s):  
D. L. Callahan
Keyword(s):  
Plastic Deformation ◽  
Aluminum Nitride ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Bright Field Image ◽  
Perfectly Plastic ◽  
Contrast Analysis ◽  
Deformation Patterns

Modern polishing, precision machining and microindentation techniques allow the processing and mechanical characterization of ceramics at nanometric scales and within entirely plastic deformation regimes. The mechanical response of most ceramics to such highly constrained contact is not predictable from macroscopic properties and the microstructural deformation patterns have proven difficult to characterize by the application of any individual technique. In this study, TEM techniques of contrast analysis and CBED are combined with stereographic analysis to construct a three-dimensional microstructure deformation map of the surface of a perfectly plastic microindentation on macroscopically brittle aluminum nitride.The bright field image in Figure 1 shows a lg Vickers microindentation contained within a single AlN grain far from any boundaries. High densities of dislocations are evident, particularly near facet edges but are not individually resolvable. The prominent bend contours also indicate the severity of plastic deformation. Figure 2 is a selected area diffraction pattern covering the entire indentation area.

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