scholarly journals First Principles Estimation of Shock Tube Tests on Nanoreinforced Composite Materials

2011 ◽  
Vol 78 (6) ◽  
Author(s):  
Weiping Xu ◽  
Elizabeth K. Ervin
Keyword(s):  
Composite Materials ◽  
Shock Tube ◽  
Response Prediction ◽  
Dynamic Monitoring ◽  
Complex Case ◽  
Mode Shapes ◽  
Extreme Loads ◽  
Experimental Shock ◽  
Specific Complex ◽  
Shock Tube Test

Extreme loads events can cause enormous human and infrastructure losses. Computer modeling is the key to reducing the high cost of dynamic monitoring and experimentation. Engineers in various fields have undertaken complicated modeling for structures under abnormal loads. However, an efficient and accurate model is necessary to more rapidly address dangerous shock problems. Composite materials have replaced metals in various applications thanks to their superior shock resistance properties. This investigation particularly relates to their usage on naval ships to achieve improved blast survivability with the additional benefit of lower cost. A relatively simple model is detailed for the approximate centerline response prediction of the specific complex case of composite materials tested in a shock tube. A modal analysis simulation of a beam is performed using gross properties as well as physical geometry and arbitrary shock. Closed form equations have been employed to derive the eigenproblem that generates mode shapes and natural frequencies, and the resulting responses are compared to experimental shock tube test results. The best outcome was generated by the simplest model consisting of a shock pressure pulse averaged in two divisions and applied over the entire beam span. For this case, the simulation and experimental responses had reasonable correlation for fractured E-glass/vinyl-ester composite specimens with both nanoclay and graphite platelet reinforcement. This model is also a conservative estimate for the transient test deflection range for all other specimens.

Straked Riser Design With VIVA

2010 ◽  
Author(s):  
Dhyanjyoti Deka ◽  
Paul R. Hays ◽  
Kamaldev Raghavan ◽  
Mike Campbell
Keyword(s):  
Traveling Waves ◽  
Oil And Gas ◽  
Cross Flow ◽  
Oil And Gas Industry ◽  
Response Prediction ◽  
Design Tool ◽  
Mode Shapes ◽  
Fe Model ◽  
Viv Suppression ◽  
Modal Solution

VIVA is a vortex induced vibration (VIV) analysis software that to date has not been widely used as a design tool in the offshore oil and gas industry. VIVA employs a hydrodynamic database that has been benchmarked and calibrated against test data [1]. It offers relatively few input variables reducing the risk of user induced variability of results [2]. In addition to cross flow current induced standing wave vibration, VIVA has the capability of predicting traveling waves on a subsea riser, or a combination of standing and traveling waves. Riser boundary conditions including fixed, pinned, flex joint or SCR seabed interaction can be modeled using springs and dashpots. VIVA calculates riser natural frequencies and mode shapes and also has the flexibility to import external modal solutions. In this paper, the applicability of VIVA for the design of straked steel catenary risers (SCR) and top tensioned risers (TTR) is explored. The use of linear and rotational springs provided by VIVA to model SCR soil interaction and flex joint articulation is evaluated. Comparisons of the VIV fatigue damage output with internal and external modal solution is presented in this paper. This paper includes validation of the VIVA generated modal solution by comparing the modal frequencies and curvatures against a finite element (FE) model of the risers. Fatigue life is calculated using long term Gulf of Mexico (GoM) currents and is compared against the industry standard software SHEAR7. Three different lift curve selections in SHEAR7 are used for this comparison. The differences in riser response prediction by the two software tools are discussed in detail. The sensitivity of the VIVA predicted riser response to the absence of VIV suppression devices is presented in this paper. The riser VIV response with and without external FE generated modal input is compared and the relative merits of the two modeling approaches are discussed. Finally, the recommended approach for VIVA usage for SCR and TTR design is given.

scholarly journals Dynamic Compensation of Piezoresistive Pressure Sensor Based on Sparse Domain

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Bo Xu ◽  
Tailin Han ◽  
Hong Liu ◽  
Xiao Wang ◽  
Mingchi Ju
Keyword(s):  
Shock Wave ◽  
Shock Tube ◽  
Test Data ◽  
Pressure Sensor ◽  
Pressure Sensors ◽  
The United States ◽  
Positive Pressure ◽  
Dynamic Compensation ◽  
Tube Test ◽  
Shock Tube Test

In the process of transient test, due to the insufficient bandwidth of the pressure sensor, the test data is inaccurate. Firstly, based on the projection of the shock tube test signal in the sparse domain, the feature expression of the signal sample is obtained. Secondly, the problem of insufficient bandwidth is solved by inverse modeling of sensor dynamic compensation system based on swarm intelligence algorithm. In this paper, the method is used to compensate the shock tube test signals of the 85XX series pressure sensors made by the Endevco company of the United States, the working bandwidth of the sensor is widened obviously, the rise time of the pressure signal can be compensated to 12.5 μs, and the overshoot can be reduced to 8.96%. The repeatability of dynamic compensation is verified for the actual gun muzzle shock wave test data, the results show that the dynamic compensation can effectively recover the important indexes such as overpressure peak value and positive pressure action time, and the original shock wave signal is recovered from the high resonance data.

Influence of turbulent boundary layer on shock tube test time

AIAA Journal ◽  
1965 ◽  
Vol 3 (5) ◽  
pp. 960-961
Author(s):  
PETER JEANMAIRE ◽  
ERIC F. BROCKER
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Shock Tube ◽  
Test Time ◽  
Tube Test ◽  
Shock Tube Test

The Pyrolysis of 3-Picoline: Ab Initio Quantum Chemical and Experimental (Shock Tube) Kinetic Studies

1996 ◽  
Vol 36 (3) ◽  
pp. 239-248 ◽  
Author(s):  
Jeffrey Jones ◽  
George B. Bacskay ◽  
John C. Mackie
Keyword(s):  
Shock Tube ◽  
Ab Initio ◽  
Quantum Chemical ◽  
Kinetic Studies ◽  
Experimental Shock

The Shockwave Response of Thin Composite Materials

2012 ◽  
Author(s):  
Douglas Jahnke ◽  
Yiannis Andreopoulos
Keyword(s):  
Composite Materials ◽  
Shock Waves ◽  
Shock Tube ◽  
Frequency Response ◽  
High Frequency ◽  
Composite Plates ◽  
Image Correlation ◽  
Flat Plates ◽  
High Frequency Response ◽  
Nominal Thickness

Impingement of blast or shock waves on structures is characterized by a substantial transient aerodynamic load that develops over the short time associated with the shock reflection time scale. This mutual interaction between the shock wave and the structure can cause significant deformation of the structure and high strain rates within the material resulting in damage. An experimental investigation was carried out to determine the aeroelastic response of thin flat plates of composite materials during face-on impact with planar shock waves. The experiments were performed in a large-scale shock tube research facility, which had a working section of 12 inches in diameter and a length of 80 ft. Phenolic composite S2-HJ1 plates of 1/8 inch nominal thickness consisting of 12 layers of fibers and epoxy composite S2 plates of 1/8 inch nominal thickness consisting of 10 layers of fibers were tested in the present investigation. Miniature semi-conductor strain-gauges of high frequency response, high speed photography and Digital Image Correlation techniques were employed to measure locally the strain on the exterior side of the plates and high frequency response pressure transducers were used to measure time-dependent wall and total pressure. In order to provide comparison with the response of monolithic material to similar compressive loadings, aluminum and stainless steel plates were also tested under the same conditions. The application of shock loading on the specimen causes significant permanent deformation on the plates which has been measured immediately after the experiment while the specimen is still mounted on the end flange of the shock tube. These experimental data obtained in the present experiments include the measured displacement of the external surface of the plates from their original position in the normal to the plate direction along the radius of the specimen. This displacement is highest at the center of the plate and zero at the location of clamping. The results show that the deformations of the thicker plates are still considerably lower than those obtained in the steel and thinner composite plates although the loading pressure is more than triple in magnitude and the corresponding impulse is about 2.3 times higher. Composite plates were found to suppress several of the modes of the wave patterns while metallic ones demonstrate a rich variety of interacting modes. The frequency content of the strain signals on the surface of composite plates was not always the same with the content of the surface acceleration measured in free vibration experiments.

Moving computational multi-domain method for modelling the flow interaction of multiple moving objects

2021 ◽  
Author(s):  
Momoha Nishimura ◽  
Masashi Yamakawa ◽  
Shinichi Asao ◽  
Seiichi Takeuchi ◽  
Mehdi Badri Ghomizad
Keyword(s):  
Flow Field ◽  
Shock Tube ◽  
Short Distance ◽  
Moving Objects ◽  
Computational Domain ◽  
Validation Test ◽  
Tube Test ◽  
Flow Interaction ◽  
Shock Tube Test ◽  
Object Move

Abstract This study proposes a method where the flow field variables are communicated between multiple separate moving computational domains and simulates the flow interaction of multiple moving objects. Instead of using the conventional approach with a single fixed computational domain covering the whole flow field, this method advances the moving computational domain (MCD) method in which the computational domain itself moves in line with the motions of an object inside. The computational domains created around each object move independently, and the flow fields of each domain interact where the flows cross. This eliminates the spatial restriction for simulating multiple moving objects. After the results of the shock tube test verify that the interpolation has been achieved between grids, a validation test is conducted in which two spheres are crossed, and the forces exerted on one object due to the other’s crossing at a short distance are calculated. The results verify the reliability of this method and show that it is applicable to the flow interaction of multiple moving objects.

The influence of boundary layer growth on shock tube test times

1968 ◽  
Vol 18 (1) ◽  
pp. 116-155 ◽  
Author(s):  
P. J. Musgrove ◽  
J. P. Appleton
Keyword(s):  
Boundary Layer ◽  
Shock Tube ◽  
Layer Growth ◽  
Tube Test ◽  
Shock Tube Test ◽  
Boundary Layer Growth

scholarly journals Identification, Model Updating, and Response Prediction of an Instrumented 15-Story Steel-Frame Building

2006 ◽  
Vol 22 (3) ◽  
pp. 781-802 ◽  
Author(s):  
Derek Skolnik ◽  
Ying Lei ◽  
Eunjong Yu ◽  
John W. Wallace
Keyword(s):  
Structural Damage ◽  
Model Updating ◽  
Three Dimensional ◽  
Response Prediction ◽  
Element Model ◽  
Ambient Vibration ◽  
Mode Shapes ◽  
Northridge Earthquake ◽  
Vibration Data ◽  
Modal Properties

Identification of the modal properties of the UCLA Factor Building, a 15-story steel moment-resisting frame, is performed using low-amplitude earthquake and ambient vibration data. The numerical algorithm for subspace state-space system identification is employed to identify the structural frequencies, damping ratios, and mode shapes corresponding to the first nine modes. The frequencies and mode shapes identified based on the data recorded during the 2004 Parkfield earthquake ( Mw=6.0) are used to update a three-dimensional finite element model of the building to improve correlation between analytical and identified modal properties and responses. A linear dynamic analysis of the updated model excited by the 1994 Northridge earthquake is performed to assess the likelihood of structural damage.

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