As-Built Geometry and Surface Finish Effects on Fatigue and Tensile Properties of Laser Fused Titanium 6Al-4V

The as-built material behavior of additive manufactured (AM) Titanium (Ti) 6Al-4V is investigated in this study. A solution heat treated, aged, stress relieved, and hot isostatic pressed Laser Powder Bed Fusion (LPBF) AM process was used to manufacture the specimens of interest. The motivation behind this work is based on the ever-growing desire of aerospace system designers to use AM to fabricate components with novel geometries. Specifically, there is keen interest in AM components with complex internal cooling configurations such as turbine blades, nozzle vanes, and heat exchangers that can improve small scale propulsion performance. Though it is feasible to three-dimensionally print parts that meet the Fit portion of a part characteristic description and identification, the Form and Function portions have proven to be more difficult to conquer. This study addresses both the Form and Function characteristics of the LPBF AM process via the investigation of geometry variation and surface roughness effects pertaining to mechanical properties and fatigue behavior of Ti 6Al-4V. Results show that geometry variation may be the cause of increased vibration fatigue life uncertainty. Also, both fatigue and tensile properties show profound discrepancies associated with surface finish. As-built surface finish specimens have lower fatigue and ductility performance, but the results are more consistent than polished data.

Download Full-text

How to chat in English and Chinese: Emerging digital language conventions

ReCALL ◽

10.1017/s0958344004000527 ◽

2004 ◽

Vol 16 (2) ◽

pp. 308-329 ◽

Cited By ~ 17

Author(s):

HEATHER LOTHERINGTON ◽

YEJUN XU

Keyword(s):

Online Communication ◽

Language Instruction ◽

Small Scale ◽

Factors Affecting ◽

Second Languages ◽

Form And Function ◽

World Languages ◽

Teachers And Students ◽

Digital Environments ◽

And Function

Rapid changes in language form and function occurring in digital environments present teachers and students of second languages alike with conundrums as to language and discourse standards. Factors affecting the changes that are emerging in digital English include the spatial and temporal possibilities and constraints of the medium, digital facilitation of case-creativity and iconic incorporation, and new social network configurations. This paper analyzes evolving changes in orthographic, syntactic, discourse and sociocultural conventions occurring in English and Chinese in digital environments, based on a small scale study conducted at York University in 2002–2003, noting trends across these languages as well as more limited, culturally and linguistically specific evolutions. The converging conventional changes occurring in these two major world languages suggest that similar transitions are happening generally in languages used for online communication, which has serious implications for second language instruction.

Download Full-text

Form and Function of Tridacna Shell Plaques from the Western Solomon Islands

Empirical Studies of the Arts ◽

10.2190/q5xv-j516-1qlq-a2pn ◽

1983 ◽

Vol 1 (1) ◽

pp. 55-74 ◽

Cited By ~ 1

Author(s):

Deborah Waite

Keyword(s):

Surface Finish ◽

Cultural Context ◽

Visual Analysis ◽

Solomon Islands ◽

Relative Thickness ◽

Clam Shell ◽

Form And Function ◽

Art Form ◽

And Function ◽

Technical Considerations

Openwork plaques made from tridacna clam shell constitute a significant art form from the Western Solomon Islands. Known facts are relatively few: the plaques were associated with burials and were sometimes used or referred to as a special form of “Custom Money.” Visual analysis of forty-two plaques or plaque fragments indicates that there are three groups separable on the basis of figure style, motifs, composition, and technical considerations such as the relative thickness of the plaques, surface finish, and the like. This article integrates known facts regarding function or use of the plaques with information about other clam shell artifacts from the same islands and with a detailed analysis of the plaques themselves so as to reconstruct something of the traditional cultural context and significance of these artifacts.

Download Full-text

Bands of brothers and in-laws: Waorani warfare, marriage and alliance formation

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2018.1859 ◽

2018 ◽

Vol 285 (1890) ◽

pp. 20181859 ◽

Cited By ~ 6

Author(s):

Shane J. Macfarlan ◽

Pamela I. Erickson ◽

James Yost ◽

Jhanira Regalado ◽

Lilia Jaramillo ◽

...

Keyword(s):

Social Relationships ◽

Strategic Alliances ◽

Quantitative Data ◽

Modern Human ◽

Intergroup Conflict ◽

Coalition Building ◽

Small Scale ◽

Alliance Formation ◽

Form And Function ◽

And Function

The root of modern human warfare lies in the lethal coalitionary violence of males in small-scale societies. However, there is a paucity of quantitative data concerning the form and function of coalitionary violence in this setting. Debates exist over how lethal coalitions are constituted, as well as the motivations and benefits for males to join such groups. Data from a lowland Amazonian population, the Waorani of Ecuador, illuminate three issues: (i) the degree to which raiding parties are composed of groups of fraternal kin as opposed to strategic alliances of actual or potential affinal kin; (ii) the extent to which individuals use pre-existing affinal ties to motivate others to participate in war or leverage warfare as a mechanism to create such ties; and (iii) the extent to which participation in raiding is driven by rewards associated with future marriage opportunities. Analyses demonstrate that Waorani raiding parties were composed of a mix of males who were potential affines, actual affines and fraternal kin, suggesting that men used pre-existing genetic, lineal and social kin ties for recruiting raid partners and used raiding as a venue to create novel social relationships. Furthermore, analyses demonstrate that males leveraged raiding alliances to achieve marriage opportunities for themselves as well as for their children. Overall, it appears that a complex set of motivations involving individual rewards, kin marriage opportunities, subtle coercion and the assessment of alliance strength promote violent intergroup conflict among the Waorani. These findings illustrate the complex inter-relationships among kin selection, coalition building and mating success in our species.

Download Full-text

Scanning tunneling microscopy (STM) of DNA and RNA

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100152148 ◽

1989 ◽

Vol 47 ◽

pp. 34-35

Author(s):

Patricia G. Arscott ◽

Gil Lee ◽

Victor A. Bloomfield ◽

D. Fennell Evans

Keyword(s):

Molecular Structures ◽

Inorganic Materials ◽

Resolving Power ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Form And Function ◽

Dna And Rna ◽

Calf Thymus ◽

And Function ◽

The Relationship

STM is one of the most promising techniques available for visualizing the fine details of biomolecular structure. It has been used to map the surface topography of inorganic materials in atomic dimensions, and thus has the resolving power not only to determine the conformation of small molecules but to distinguish site-specific features within a molecule. That level of detail is of critical importance in understanding the relationship between form and function in biological systems. The size, shape, and accessibility of molecular structures can be determined much more accurately by STM than by electron microscopy since no staining, shadowing or labeling with heavy metals is required, and there is no exposure to damaging radiation by electrons. Crystallography and most other physical techniques do not give information about individual molecules.We have obtained striking images of DNA and RNA, using calf thymus DNA and two synthetic polynucleotides, poly(dG-me5dC)·poly(dG-me5dC) and poly(rA)·poly(rU).

Download Full-text