15,761 research outputs found
Long term availability of raw experimental data in experimental fracture mechanics
Experimental data availability is a cornerstone for reproducibility in
experimental fracture mechanics, which is crucial to the scientific method.
This short communication focuses on the accessibility and long term
availability of raw experimental data. The corresponding authors of the eleven
most cited papers, related to experimental fracture mechanics, for every year
from 2000 up to 2016, were kindly asked about the availability of the raw
experimental data associated with each publication. For the 187 e-mails sent:
22.46% resulted in outdated contact information, 57.75% of the authors did
received our request and did not reply, and 19.79 replied to our request. The
availability of data is generally low with only available data sets
(5.9%). The authors identified two main issues for the lacking availability of
raw experimental data. First, the ability to retrieve data is strongly attached
to the the possibility to contact the corresponding author. This study suggests
that institutional e-mail addresses are insufficient means for obtaining
experimental data sets. Second, lack of experimental data is also due that
submission and publication does not require to make the raw experimental data
available. The following solutions are proposed: (1) Requirement of unique
identifiers, like ORCID or ResearcherID, to detach the author(s) from their
institutional e-mail address, (2) Provide DOIs, like Zenodo or Dataverse, to
make raw experimental data citable, and (3) grant providing organizations
should ensure that experimental data by public funded projects is available to
the public
Initial planetary base construction techniques and machine implementation
Conceptual designs of (1) initial planetary base structures, and (2) an unmanned machine to perform the construction of these structures using materials local to the planet are presented. Rock melting is suggested as a possible technique to be used by the machine in fabricating roads, platforms, and interlocking bricks. Identification of problem areas in machine design and materials processing is accomplished. The feasibility of the designs is contingent upon favorable results of an analysis of the engineering behavior of the product materials. The analysis requires knowledge of several parameters for solution of the constitutive equations of the theory of elasticity. An initial collection of these parameters is presented which helps to define research needed to perform a realistic feasibility study. A qualitative approach to estimating power and mass lift requirements for the proposed machine is used which employs specifications of currently available equipment. An initial, unmanned mission scenario is discussed with emphasis on identifying uncompleted tasks and suggesting design considerations for vehicles and primitive structures which use the products of the machine processing
Space Transportation Materials and Structures Technology Workshop
The Space Transportation Materials and Structures Technology Workshop was held on September 23-26, 1991, in Newport News, Virginia. The workshop, sponsored by the NASA Office of Space Flight and the NASA Office of Aeronautics and Space Technology, was held to provide a forum for communication within the space materials and structures technology developer and user communities. Workshop participants were organized into a Vehicle Technology Requirements session and three working panels: Materials and Structures Technologies for Vehicle Systems, Propulsion Systems, and Entry Systems
Reliability analysis and micromechanics: A coupled approach for composite failure prediction
This work aims at associating two classical approaches for the design of composite materials: first, reliability methods that allow to account for the various uncertainties involved in the composite materials behaviour and lead to a rational estimation of their reliability level; on the other hand, micromechanics that derive macroscopic constitutive laws from micromechanical features. Such approach relies on the introduction of variabilities defined at the microscale and on the investigation of their consequences on the material macroscopic response through an homogenization scheme. Precisely, we propose here a systematic treatment of variability which involves a strong link between micro- and macroscales and provides a more exhaustive analysis of the influence of uncertainties. The paper intends to explain the main steps of such coupling and demonstrate its interests for material engineering, especially for constitutive modelling and composite materials optimization. An application case is developed throughout on the failure of unidirectional carbon fibre-reinforced composites with a comparative analysis between experimental data and simulation results
Applications of aerospace technology in the electric power industry
An overview of the electric power industry, selected NASA contributions to progress in the industry, linkages affecting the transfer and diffusion of technology, and, finally, a perspective on technology transfer issues are presented
Concepts and techniques for ultrasonic evaluation of material mechanical properties
Ultrasonic methods that can be used for material strength are reviewed. Emergency technology involving advanced ultrasonic techniques and associated measurements is described. It is shown that ultrasonic NDE is particularly useful in this area because it involves mechanical elastic waves that are strongly modulated by morphological factors that govern mechanical strength and also dynamic failure modes. These aspects of ultrasonic NDE are described in conjunction with advanced approaches and theoretical concepts for signal acquisition and analysis for materials characterization. It is emphasized that the technology is in its infancy and that much effort is still required before the techniques and concepts can be transferred from laboratory to field conditions
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