scholarly journals Aspects of Strength Testing of Tank Containers in Compliance with the Requirements of the UN Navigation Rules and Regulations

2021 ◽  
Vol 9 (3) ◽  
pp. 349
Author(s):  
Andrii Sulym ◽  
Pavlo Khozia ◽  
Eduard Tretiak ◽  
Václav Píštěk ◽  
Oleksij Fomin ◽  
...  
Keyword(s):  
Natural Frequencies ◽  
Response Spectrum ◽  
Experimental Curve ◽  
Bulk Liquid ◽  
Frequency Range ◽  
Test Configuration ◽  
Shock Response ◽  
Shock Response Spectrum ◽  
Spectrum Curve ◽  
The Impact

This article deals with the method of computer-aided studies of the results of tank container impact tests to confirm the ability of portable tanks and multi-element gas containers to withstand the impact in the longitudinal direction on a specially equipped test rig or using a railway flat car by impacting a flat car with a striking car, in compliance with the requirements of the UN Navigation Rules and Regulations. It is shown that the main assessed characteristic of the UN requirements is the spectrum of the shock response (accelerations) for the interval natural frequencies of the shock pulse. The calculation of the points of the shock response spectrum curve based on the test results is reproduced in four stages. A test configuration of the impact testing of the railway flat car with a tank container is presented, and the impact is performed in such a way that, under a single impact, the shock spectrum curve obtained during the tests for both fittings subjected to impact repeats or exceeds the minimum shock spectrum curve for all frequencies in the range of 2 Hz to 100 Hz. Formulas for determining the relative displacements and accelerations for the interval natural frequencies of the shock wave are given. The research results are presented in graphical form, indicating that the experimental values of the shock response spectrum exceed the minimum permissible values; the equation of the experimental curve of the shock response spectrum in the frequency range 0–100 Hz is described by power-law dependence. The coefficients of the equation were determined by the statistical method of maximum likelihood with the determination factor being 0.897, which is a satisfactory value; a comparative analysis showed that the experimental curve of the impact response spectrum in the frequency range 0–100 Hz exceeds the normalized curve, which confirms compliance with regulatory requirements. A new test configuration is proposed using a tank car with a bulk liquid, the processes in which upon impact differ significantly from other freight wagons under longitudinal impact loads of the tank container. The hydraulic impact resulting from the impact on the tank container and the platform creates an overturning moment that causes the rear fittings to be unloaded.

scholarly journals ASPECTS OF TANK-CONTAINER TESTS FOR COMPLIANCE WITH THE REQUIREMENTS OF THE UN SHIPPING REGISTER

2020 ◽  
pp. 7-27
Author(s):  
E.V. Tretiak ◽  
Keyword(s):  
Natural Frequencies ◽  
Response Spectrum ◽  
Experimental Curve ◽  
Impact Response ◽  
Bulk Liquid ◽  
Graphical Form ◽  
Impact Loads ◽  
Frequency Range ◽  
Test Configuration ◽  
The Impact

The article deals the method of calculation studies of impact tests of tank containers to confirm the ability of portable tanks and multi-element gas containers to withstand the impact in the longitudinal direction on a specially equipped stand accredited in the certification system of the Register of Shipping of Ukraine, or using a railway platform and executing an impact force generated by a wagon-striker in accordance with the requirements of the UN Register of Shipping. It is shown that the main estimated characteristic of the UN requirements is the impact response spectrum (accelerations) for the interval natural frequencies of the impact impulse. The calculation of the points of the impact response spectrum curve according to the test results is shown in four stages. The test configuration of a railway platform with a tank-container for impact loads is presented, in which the impact is performed in such a way that the curve of the impact response spectrum obtained during the tests of both fittings under a single impact repeated or exceeded the minimum impact response curve spectrum at all frequencies in the range from 2 Hz to 100 Hz. The matrices of relative displacements and accelerations for the interval natural frequencies of the impact wave are given. The results of the research are presented in graphical form, which shows that the experimental values of the impact response spectrum exceed the minimum allowable values. The equation of the experimental curve of the shock response spectrum in the frequency range 0-100 Hz is described by the power dependence; the coefficients of the equation were determined by the statistical method of the maximum likelihood, with the determination factor being 0.897, which is a satisfactory value. The comparative analysis showed that the experimental curve of the impact response spectrum in the frequency range 0-100 Hz exceeds the normalized curve, which confirms compliance with regulatory requirements. It is proposed to use a new test configuration using a tank car with bulk liquid, where the processes occurring under impact significantly differ from other freight cars subjected to longitudinal impact loads of the tank container. The hydraulic shock caused by the impact on the tank container and the platform creates a turning moment, which causes the rear fittings to be unloaded.

scholarly journals Dynamic Wheel-Rail Forces on Mismatched Joints With Ramps

2016 ◽  
Author(s):  
Brian Marquis ◽  
Robert Greif
Keyword(s):  
Impact Force ◽  
Response Spectrum ◽  
Track Structure ◽  
Repeated Impact ◽  
Safety Standards ◽  
Impact Forces ◽  
Shock Response ◽  
Shock Response Spectrum ◽  
Maximum Impact Force ◽  
The Impact

The discontinuity between rail ends at a joint creates dynamic wheel-rail forces (i.e. high impact forces and wheel unloading) that can result in a range of problems including wear, deterioration, and early failure of the track structure, its components, and passing equipment. The response and magnitude of the dynamic wheel-rail forces generated at joints depend upon the form of the discontinuity (e.g. battered rail ends, ramps, gaps, mismatches, etc.) and the support condition. Joints with battered rail ends, which result from degradation due to repeated impact loading, have been extensively analyzed using closed form expressions developed by Jenkins [1] to estimate P1 and P2 impact forces. While appropriate for analyzing joints with battered rail ends, P1 and P2 forces are not directly applicable to other forms of discontinuity at joints such as mismatches in which the rail ends are offset vertically when installed. Under certain circumstances, railroads are introducing ramps (by grinding or welding) to reduce the mismatch discontinuity and produce a smoother transition in order to mitigate these dynamic wheel-rail forces. In this paper, analyses are conducted to estimate dynamic wheel-rail forces at joints having ramps and mismatches of various sizes using simplified models along with detailed NUCARS models for comparative purposes. The Federal Railroad Administration (FRA) Track Safety Standards (49 CFR Part213) [2] limit the maximum mismatch at joints by Track Class in order to minimize the impact forces which deteriorate the track structure, its components, and equipment, and may ultimately lead to derailment. Parametric studies are conducted to examine the effects of ramp length, direction of travel, mismatch height, and equipment speed (track class). Plots of primary shock-response-spectrum (maximum impact force on the ramp), residual shock-response-spectrum (maximum impact force after the ramp), and minimum wheel force (i.e. wheel unloading) are developed to provide guidelines on ramp length (H-rule) in order to control the maximum force by track class.

Analytical Determination of Shock Response Spectra for an Impulse-Loaded Proportionally Damped System

Volume 1 ◽  
2004 ◽  
Author(s):  
R. David Hampton ◽  
Nathan S. Wiedenman ◽  
Ting H. Li
Keyword(s):  
Transient Response ◽  
Shock Loading ◽  
Response Spectrum ◽  
Response Spectra ◽  
Analytical Determination ◽  
System Response ◽  
Mechanical Shock ◽  
Shock Response ◽  
Mass Spring ◽  
The Impact

Many military systems must be capable of sustained operation in the face of mechanical shocks due to projectile or other impacts. The most widely used method of quantifying a system’s vibratory transient response to shock loading is called the shock response spectrum (SRS). The system response for which the SRS is to be determined can be due, physically, either to a collocated or to a noncollocated shock loading. Taking into account both possibilities, one can define the SRS as follows: the SRS presents graphically the maximum transient response (output) of an imaginary ideal mass-spring-damper system at one point on a flexible structure, to a particular mechanical shock (input) applied to an arbitrary (perhaps noncollocated) point on the structure, as a function of the natural frequency of the imaginary mass-spring-damper system. For a response point sufficiently distant from the impact area, many Army platforms (such as vehicles) can be accurately treated as linear systems with proportional damping. In such cases the output due to an impulsive mechanical-shock input can be decomposed into exponentially decaying sinusoidal components, using normal-mode orthogonalization. Given a shock-induced loading comprising such components, this paper provides analytical expressions for the various common SRS forms. The analytical approach to SRS-determination can serve as a verification of, or an alternative to, the numerical approaches in current use for such systems. No numerical convolution is required, because the convolution integrals have already been accomplished analytically (and exactly), with the results incorporated into the algebraic expressions for the respective SRS forms.

Swept Sine Vibration Test Conservatism

1995 ◽  
Vol 38 (6) ◽  
pp. 13-17
Author(s):  
M. Hine
Keyword(s):  
Response Spectrum ◽  
Three Dimensional ◽  
Test Method ◽  
Vibration Test ◽  
Transient Vibration ◽  
Mass Model ◽  
Dynamic Mass ◽  
Shock Response ◽  
Order Of Magnitude ◽  
Shock Response Spectrum

The excessive overtest associated with the swept sine vibration test method was measured quantitatively using the index of conservatism and the associated overtest factor for a dynamic mass model of a typical spacecraft component. The response to a fixed amplitude sine sweep test was compared with the flight transient vibration environment for sweep rates of 2, 4, and 6 octaves/min and 300 Hz/min. A response-limited test was also conducted at 6 octaves/min. The conservatism was measured using several characterizations; namely: number of peaks exceeding, ranked peaks, shock response spectrum, shock intensity, three-dimensional shock response spectrum, and ranked peaks. Overtest factors exceeding an order of magnitude were measured for the test response with the number of peaks exceeding and the three-dimensional shock response spectrum.

scholarly journals The Shock Characteristics of Tilted Support Spring Packaging System with Critical Components

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
An-Jun Chen
Keyword(s):  
Frequency Ratio ◽  
Response Spectrum ◽  
Three Dimensional ◽  
Frequency Parameter ◽  
Mass Ratio ◽  
Packaging System ◽  
Parameter Ratio ◽  
Shock Response ◽  
Shock Response Spectrum ◽  
Critical Components

The nonlinear dynamical equations of tilted support spring packaging system with critical components were obtained under the action of half-sine pulse. To evaluate the shock characteristics of the critical components, a new concept of three-dimensional shock response spectrum was proposed. The ratio of the maximum shock response acceleration of the critical components to the peak pulse acceleration, the dimensionless pulse duration, and the frequency parameter ratio of system or the angle of tilted support spring system were three basic parameters of the three-dimensional shock response spectrum. Based on the numerical results, the effects of the peak pulse acceleration, the angle of the tilted support spring, the frequency parameter ratio, and the mass ratio on the shock response spectrum were discussed. It is shown that the effects of the angle of the tilted support spring and the frequency ratio on the shock response spectrum are particularly noticeable, increasing frequency parameter ratio of the system can obviously decrease the maximum shock response acceleration of the critical components, and the peak of the shock response of the critical components can be decreased at low frequency ratio by increasing mass ratio.

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