Nondestructive Evaluation of FRP Design Criteria With Primary Consideration to Fatigue Loading

2004 ◽  
Vol 126 (2) ◽  
pp. 216-228 ◽  
Author(s):  
Guillermo Ramirez ◽  
Paul H. Ziehl ◽  
Timothy J. Fowler
Keyword(s):  
Nondestructive Evaluation ◽  
State Of The Art ◽  
Accurate Determination ◽  
Fatigue Loading ◽  
Pressure Vessels ◽  
Allowable Level ◽  
Strength Tests ◽  
Recorded Performances ◽  
Better Than

Design of FRP tanks and pressure vessels is based on criteria developed in the late 1960s using materials and procedures that represented the state of the art at the time. Maximum strain has been the controlling factor selected for the design of these vessels at an allowable level of 0.001. With the development of newer materials and systems with recorded performances of better than 0.001 this is now an inefficient limit in the design. Tests performed in the programs described in this paper indicate that newer materials perform well at higher strains. Results of strength tests performed here indicated that strains of 0.002 to 0.003 or better are possible in the safe design of tanks and pressure vessels. In addition, more accurate determination of design limits is possible if methods like acoustic emission are incorporated in the design process.

A New Approach for Determining Joint Stiffness of Bolted Joints

2014 ◽  
Vol 670-671 ◽  
pp. 1041-1044 ◽  
Author(s):  
Xi Wang Wang ◽  
Xiao Yang Li ◽  
Lin Lin Zhang ◽  
Xiao Guang Wang
Keyword(s):  
Accurate Determination ◽  
Joint Stiffness ◽  
Fatigue Loading ◽  
Bolted Joints ◽  
Analytical Models ◽  
Bolted Connection ◽  
New Approach ◽  
Axisymmetric Model ◽  
Force Equilibrium

Joint member stiffness in a bolted connection directly influence the safety of a design in regard to both static and fatigue loading as well as in the prevention of separation in the connection. Thus, the accurate determination of the stiffness is of extreme importance to predict the behavior of bolted assemblies. In this paper, An analytical 3D axisymmetric model of bolted joints is proposed to obtain the joint stiffness of Bolted Joints. Considering many different analytical models have been proposed to calculate the joint stiffness, the expression based force equilibrium can be a easy way to choose the best expression for the joint stiffness as a judgment criteria.

Design Formulas of Blind End Closures for High Pressure Vessels

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
R. D. Dixon ◽  
E. H. Perez
Keyword(s):  
High Pressure ◽  
Fatigue Life ◽  
Maximum Stress ◽  
Accurate Determination ◽  
Pressure Vessels ◽  
Stress Distributions ◽  
Fatigue And Fracture ◽  
Asme Code ◽  
Section Viii

The available design formulas for flat heads and blind end closures in the ASME Code, Section VIII, Divisions 1 and 2 are based on bending theory and do not apply to the design of thick flat heads used in the design of high pressure vessels. This paper presents new design formulas for thickness requirements and determination of peak stresses and stress distributions for fatigue and fracture mechanics analyses in thick blind ends. The use of these proposed design formulas provide a more accurate determination of the required thickness and fatigue life of blind ends. The proposed design formulas are given in terms of the yield strength of the material and address the fatigue strength at the location of the maximum stress concentration factor. Introduction of these new formulas in a nonmandatory appendix of Section VIII, Division 3 is recommended after committee approval.

scholarly journals Sulfur dioxide layer height retrieval from Sentinel-5 Precursor/TROPOMI using FP_ILM

2019 ◽  
Vol 12 (10) ◽  
pp. 5503-5517 ◽  
Author(s):  
Pascal Hedelt ◽  
Dmitry S. Efremenko ◽  
Diego G. Loyola ◽  
Robert Spurr ◽  
Lieven Clarisse
Keyword(s):  
Sulfur Dioxide ◽  
Accurate Determination ◽  
Volcanic Eruptions ◽  
Critical Parameters ◽  
Layer Height ◽  
Learning Machine ◽  
The Impact ◽  
First Time ◽  
Better Than

Abstract. The accurate determination of the location, height, and loading of sulfur dioxide (SO2) plumes emitted by volcanic eruptions is essential for aviation safety. The SO2 layer height is also one of the most critical parameters with respect to determining the impact on the climate. Retrievals of SO2 plume height have been carried out using satellite UV backscatter measurements, but, until now, such algorithms are very time-consuming. We have developed an extremely fast yet accurate SO2 layer height retrieval using the Full-Physics Inverse Learning Machine (FP_ILM) algorithm. This is the first time the algorithm has been applied to measurements from the TROPOMI instrument onboard the Sentinel-5 Precursor platform. In this paper, we demonstrate the ability of the FP_ILM algorithm to retrieve SO2 plume layer heights in near-real-time applications with an accuracy of better than 2 km for SO2 total columns larger than 20 DU. We present SO2 layer height results for the volcanic eruptions of Sinabung in February 2018, Sierra Negra in June 2018, and Raikoke in June 2019, observed by TROPOMI.

Confirmation of the new technique for measuring the linear thermal expansion of silicon

1993 ◽  
Vol 8 (1) ◽  
pp. 36-38 ◽  
Author(s):  
Liu Fengchao
Keyword(s):  
Thermal Expansion ◽  
Room Temperature ◽  
Accurate Determination ◽  
Linear Thermal Expansion ◽  
Linear Expansion Coefficient ◽  
X Ray ◽  
High Purity Silicon ◽  
Different Temperatures ◽  
Better Than

This paper further confirms that the direct measurement of diffraction angles at different temperatures by using the X-ray diffractometer is better than measurement of the lattice parameters for the rapid and accurate determination of the linear thermal expansion of silicon. High purity silicon has the linear expansion coefficient, α= (2.45±0.05) × 10−6/°C at room temperature. This value does not change for doped P-type and N-type silicon.

Theoretical and experimental developments for accurate determination of crystallinity of cellulose I materials

2010 ◽  
Vol 44 (1) ◽  
pp. 184-192 ◽  
Author(s):  
Carlos Driemeier ◽  
Guilherme A. Calligaris
Keyword(s):  
Accurate Determination ◽  
Dry Weight ◽  
Orientation Distribution ◽  
X Ray Diffraction ◽  
Cellulose I ◽  
Experimental Development ◽  
X Ray ◽  
Pure Cellulose ◽  
Better Than

This work defines the crystallinity of cellulose I materials on a dry-weight basis. Theoretical and experimental developments in X-ray diffraction lead to a crystallinity determination method that is estimated to reach 1σ accuracies of better than 0.05 (crystallinity defined between 0 and 1). The method is based on Rietveld modelling, to resolve cellulose I Bragg peaks, and a standard truncated invariant integral. Corrections are derived to account for incoherent scattering, moisture content and other compositional deviations from pure cellulose. The experimental development uses X-ray diffraction in transmission fibre geometry with two-dimensional pattern Rietveld modelling, including a crystal-orientation distribution function. The crystallinities of a few commercial cellulose I materials were determined with the aim of illustrating the applicability of the method.

scholarly journals Recent Helioseismological Results from Space: Solar p-mode Oscillations from IPHIR on the PHOBOS Mission

1990 ◽  
Vol 121 ◽  
pp. 279-288
Author(s):  
C. Fröhlich ◽  
T. Toutain ◽  
R.M. Bonnet ◽  
A.V. Bruns ◽  
J.P. Delaboudinière ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Accurate Determination ◽  
Spectral Irradiance ◽  
High Signal ◽  
Line Shapes ◽  
Solar Spectral Irradiance ◽  
Evaluation Of Data ◽  
Very High ◽  
Better Than

AbstractIPHIR (Interplanetary Helioseismology by IRradiance measurements) is a solar irradiance experiment on the USSR planetary mission PHOBOS to Mars and its satellite Phobos. The experiment was built by an international consortium including PMOD/WRC, LPSP, SSD/ESA, KrAO and CRIP. The sensor is a three channel sunphotometer (SPM) which measures the solar spectral irradiance at 335, 500 and 865 nm with a precision of better than 1 part-per-million (ppm). It is the first experiment dedicated to the investigation of solar oscillations from space. The results presented here are from a first evaluation of data gathered during 160 days of the cruise phase of PHOBOS II, launched on July, 12th 1988. The long uninterrupted observation produces a spectrum of the solar p-mode oscillations in the 5-minute range with a very high signal-to-noise ratio, which allows an accurate determination of frequencies and line shapes of these modes.

scholarly journals An Advanced Method to Estimate Deep Currents from Profiling Floats

2005 ◽  
Vol 22 (8) ◽  
pp. 1294-1304 ◽  
Author(s):  
Jong Jin Park ◽  
Kuh Kim ◽  
Brian A. King ◽  
Stephen C. Riser
Keyword(s):  
Indian Ocean ◽  
Accurate Determination ◽  
New Method ◽  
Advanced Method ◽  
Subsurface Ocean ◽  
Least Squares Fit ◽  
Geostrophic Shear ◽  
The Mean ◽  
Better Than

Abstract Subsurface ocean currents can be estimated from the positions of drifting profiling floats that are being widely deployed for the international Argo program. The calculation of subsurface velocity depends on how the trajectory of the float while on the surface is treated. The following three aspects of the calculation of drift velocities are addressed: the accurate determination of surfacing and dive times, a new method for extrapolating surface and dive positions from the set of discrete Argos position fixes, and a discussion of the errors in the method. In the new method described herein, the mean drift velocity and the phase and amplitude of inertial motions are derived explicitly from a least squares fit to the set of Argos position fixes for each surface cycle separately. The new method differs from previous methods that include prior assumptions about the statistics of inertial motions. It is concluded that the endpoints of the subsurface trajectory can be estimated with accuracy better than 1.7 km (East Sea/Sea of Japan) and 0.8 km (Indian Ocean). All errors, combined with the error that results from geostrophic shear and extrapolation, should result in individual subsurface velocity estimates with uncertainty of the order of 0.2 cm s−1.

State-of-the-Art Least Square Support Vector Machine Application for Accurate Determination of Natural Gas Viscosity

2013 ◽  
Vol 53 (2) ◽  
pp. 945-958 ◽  
Author(s):  
Amir Fayazi ◽  
Milad Arabloo ◽  
Amin Shokrollahi ◽  
Mohammad Hadi Zargari ◽  
Mohammad Hossein Ghazanfari
Keyword(s):  
Support Vector Machine ◽  
Natural Gas ◽  
State Of The Art ◽  
Accurate Determination ◽  
Least Square ◽  
Support Vector ◽  
Gas Viscosity

scholarly journals Corrections to the Hipparcos proper motions in declination for 807 stars

2008 ◽  
pp. 109-113 ◽  
Author(s):  
G. Damljanovic ◽  
N. Pejovic
Keyword(s):  
Accurate Determination ◽  
Annual Number ◽  
Time Interval ◽  
Proper Motions ◽  
Hipparcos Catalogue ◽  
Time Variations ◽  
Better Than ◽  
Good Agreement

We used the data on latitude variations obtained from observations with 10 classical photographic zenith tubes (PZT) in order to improve the Hipparcos proper motions in declinations ?? for 807 stars. Part of observing programmes, carried out during the last century for the purpose of studying the Earth's rotation, were realized by using PZT instruments. These observations were performed within in the intervals (tens of years) much longer than that of the Hipparcos mission (less than 4 years). In addition, the annual number of observations for every PZT programme star is several hundreds on the average. Though the accuracy of the star coordinates in the Hipparcos Catalogue is by two orders of magnitude better than that of the star coordinates from the PZT observations, the large number of observations performed a much longer time interval makes it possible to correct the Hipparcos proper motions and to improve their accuracy with respect to the accuracy given in the Hipparcos Catalogue. Long term examinations of latitude and time variations were used to form the Earth Orientation Catalogue (EOC-2), aimed at a more accurate determination of positions and proper motions for the stars included. Our method of calculating the corrections of the proper motions in declination from the latitude variations is different from the method used in obtaining the EOC-2 Catalogue. Comparing the results we have established a good agreement between our ?? and the EOC-2 ones for the star sample used in the present paper.

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