scholarly journals Analysis of a Tubular Torsionally Resonating Viscosity–Density Sensor

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3036
Author(s):  
Daniel Brunner ◽  
Joe Goodbread ◽  
Klaus Häusler ◽  
Sunil Kumar ◽  
Gernot Boiger ◽  
...  
Keyword(s):  
Numerical Model ◽  
Numerical Models ◽  
Experimental Results ◽  
Static Case ◽  
Flow Loop ◽  
Actual Measurement ◽  
Wide Range ◽  
Laminar And Turbulent Flow ◽  
The Impact ◽  
Good Agreement

This paper discusses a state-of-the-art inline tubular sensor that can measure the viscosity–density ( ρ η ) of a passing fluid. In this study, experiments and numerical modelling were performed to develop a deeper understanding of the tubular sensor. Experimental results were compared with an analytical model of the torsional resonator. Good agreement was found at low viscosities, although the numerical model deviated slightly at higher viscosities. The sensor was used to measure viscosities in the range of 0.3–1000 mPa·s at a density of 1000 kg/m3. Above 50 mPa·s, numerical models predicted viscosity within ±5% of actual measurement. However, for lower viscosities, there was a higher deviation between model and experimental results up to a maximum of ±21% deviation at 0.3 mPa·s. The sensor was tested in a flow loop to determine the impact of both laminar and turbulent flow conditions. No significant deviations from the static case were found in either of the flow regimes. The numerical model developed for the tubular torsional sensor was shown to predict the sensor behavior over a wide range, enabling model-based design scaling.

Effect of Shear in Transverse Impact on Beams

1951 ◽  
Vol 165 (1) ◽  
pp. 176-188 ◽  
Author(s):  
D. G. Christopherson
Keyword(s):  
Elastic Wave ◽  
Shear Stiffness ◽  
Bending Stiffness ◽  
Experimental Results ◽  
Maximum Force ◽  
Transverse Impact ◽  
Wide Range ◽  
The Impact ◽  
Dominant Part ◽  
Good Agreement

In this paper the problem of transverse impact on a uniform beam is considered theoretically. Two examples which can be taken as representing a wide range of impacts which occur in practice are referred to particularly: (1) the beam struck transversely by a uniform square-ended rod travelling perpendicularly to it; (2) the same problem for the striker having a spherical end. In these examples it is shown that the ability of the beam to deflect in shear as well as in bending plays a dominant part in what takes place, and that, as far as the force between striker and beam is concerned, the length of the beam is usually without importance, as there is not time during the impact for an elastic wave to travel to the ends of the beam and return. It is shown that in regard to example (2) the theory presented is in good agreement with Arnold's experimental results obtained some years previously, and curves are given from which the maximum force between beam and striker can be obtained in terms of three parameters, representing respectively the velocity, the mass, and the radius of the striker, each dependent on the ratio of shear stiffness to bending stiffness for the beam.

Ballistic performance of quasi-isotropic CFRP laminates under low velocity impact

2021 ◽  
pp. 002199832110238
Author(s):  
Gyanesh Patnaik ◽  
Anshul Kaushik ◽  
Abhishek Rajput ◽  
Guru Prakash ◽  
R Velmurugan
Keyword(s):  
Numerical Model ◽  
Experimental Results ◽  
Low Velocity Impact ◽  
Fiber Reinforced ◽  
Low Velocity ◽  
Ballistic Performance ◽  
Velocity Impact ◽  
Cfrp Laminates ◽  
Wide Range ◽  
The Impact

The perforation characteristics of fiber reinforced laminates is crucial for the design of protective civil and military structures. This paper investigates the perforation characteristics (ballistic limit velocity, residual velocity, perforation energy) of cross ply and quasi-isotropic (QI) carbon fiber reinforced polymer (CFRP) laminates under the impact of a rigid conical steel bullet. The influence of thickness and ply orientation on these characteristics is also studied for a wide range of velocities. The perforation characteristics of these laminates were determined, numerically as well as experimentally. A numerical model is developed by using Hashin damage model to understand the behavior of laminates under high velocity impact. The accuracy of the model is assessed by comparing its prediction with experimental results of cross ply laminates. Then, impact perforation study of different possible configurations made of quasi-isotropic (QI) CFRP laminates, oriented at 0°, 90°, 45° and −45° directions are carried out with the help of validated numerical model. The perforation characteristics predicted with the help of numerical model is in good agreement with the experimental results. Optimal configuration is achieved in terms of energy absorption and damage resistance for better performance under impact loading.

scholarly journals Edge Cooling of a Fuel Cell during Aerial Missions by Ambient Air

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1432
Author(s):  
Lev Zakhvatkin ◽  
Alex Schechter ◽  
Eilam Buri ◽  
Idit Avrahami
Keyword(s):  
Fuel Cell ◽  
Numerical Model ◽  
Wind Tunnel ◽  
Boundary Conditions ◽  
Air Temperature ◽  
Numerical Models ◽  
Heat Removal ◽  
Ambient Air ◽  
Experimental Setup ◽  
Good Agreement

During aerial missions of fuel-cell (FC) powered drones, the option of FC edge cooling may improve FC performance and durability. Here we describe an edge cooling approach for fixed-wing FC-powered drones by removing FC heat using the ambient air during flight. A set of experiments in a wind tunnel and numerical simulations were performed to examine the efficiency of FC edge cooling at various flight altitudes and cruise speeds. The experiments were used to validate the numerical model and prove the feasibility of the proposed method. The first simulation duplicated the geometry of the experimental setup and boundary conditions. The calculated temperatures of the stack were in good agreement with those of the experiments (within ±2 °C error). After validation, numerical models of a drone’s fuselage in ambient air with different radiator locations and at different flight speeds (10–30 m/s) and altitudes (up to 5 km) were examined. It was concluded that onboard FC edge cooling by ambient air may be applicable for velocities higher than 10 m/s. Despite the low pressure, density, and Cp of air at high altitudes, heat removal is significantly increased with altitude at all power and velocity conditions due to lower air temperature.

Risk Analysis of Live Fire Shoot House Containment Systems Against Multiple Projectile Impacts

2020 ◽  
Author(s):  
Steven D. Andreen ◽  
Brad G. Davis
Keyword(s):  
Normal Distribution ◽  
Numerical Models ◽  
Single Point ◽  
Experimental Results ◽  
Risk Level ◽  
Triangular Distribution ◽  
Repeated Impact ◽  
Steel Panels ◽  
The Impact ◽  
Projectile Impacts

Abstract Many analytical and numerical models exist that can describe the effect of single projectile impacts on steel targets. These models are not adequate for the evaluation of live fire shoot house containment systems, which are subjected to repeated impact loading from small caliber projectiles over the lifetime of the structure. Models assuming perfectly rigid projectiles over-predict penetration depths. Models assuming rigid targets cannot predict any penetration, and hydrodynamic models are best suited to high velocity impacts well above the ranges of conventional ordinance. Development of sufficient analytical or numerical tools using traditional techniques would be either intractable, empirically based and unique to a given scenario, require unique material properties that are not commonly available, or require significant computational effort. Due to the limited amount of empirical data on multiple impact failure, classical reliability methods are not suitable for assessing the probability of containment system perforation. Using existing experimental results of .223 caliber ammunition against AR500 steel panels with 2-inch ballistic rubber, a commonly found protective system in these facilities, the cumulative effects of multiple projectiles were quantified to estimate the number of impacts required to perforate the target material. Impacts were simulated from normal distributions of the x and y coordinates describing the impact point using a cartesian coordinate plane. The impact resistance of the steel was also simulated from a triangular distribution to account for the variability of the experimental results. Monte Carlo Simulation was then used to estimate the expected number of impacts to cause failure at a single point on the target. Using this collective model, it was possible to determine that the distribution of the number of rounds to cause target failure approached a normal distribution. The results indicated that the mean impacts at failure was 11800 with a standard deviation of 800 impacts. Finally, targeting the allowable risk level for structural failure from the JCSS probabilistic model code from the simulated normal distribution, it was determined that the safe number of impacts was approximately 7996. Decision makers can utilize the safe number of impacts to inform training guidance for the future use of facilities and to develop effective inspection requirements. This model can also be adapted to evaluate similar training facilities and to assess how other small caliber projectile impacts would affect live fire shoot house containment systems, providing a useful tool for the design and analysis of future and the assessment of existing facilities for use with ammunition that did not exist during its design.

Experimental Validation of Computer Models for Food and Polymer Extrusion

2003 ◽  
Author(s):  
Yogesh Jaluria
Keyword(s):  
Numerical Modeling ◽  
Numerical Models ◽  
Strong Support ◽  
Chemical Conversion ◽  
Operating Conditions ◽  
Experimental Results ◽  
Twin Screw Extruders ◽  
Twin Screw ◽  
Temperature Dependent Properties ◽  
Good Agreement

The accuracy and validity of the mathematical and numerical modeling of extruders for polymers and for food are considered in terms of experimental results obtained on typical full-size single and twin-screw extruders. The fluid is treated as non-Newtonian and with strong temperature-dependent properties. The chemical conversion of food during extrusion is also considered. The numerical modeling is employed for steady-state transport, for a range of operating conditions. Following grid-independence studies, the results obtained are first considered in terms of the expected physical behavior of the process, yielding good agreement with observations presented in the literature. The results are then compared with detailed and qualitative experimental results available from previous investigations to evaluate their accuracy. Good agreement with experimental data is obtained, lending strong support to the mathematical and numerical models.

scholarly journals FINAL DESIGN OF THE NAGS HEAD BEACH NOURISHMENT PROJECT USING A LONGSHORE NUMERICAL MODEL

2012 ◽  
Vol 1 (33) ◽  
pp. 64 ◽  
Author(s):  
Haiqing Liu Kaczkowski ◽  
Timothy W Kana
Keyword(s):  
Numerical Model ◽  
Large Scale ◽  
Numerical Models ◽  
Normal Wave ◽  
Beach Nourishment ◽  
Shoreline Evolution ◽  
Longshore Transport ◽  
Final Design ◽  
Model Setup ◽  
The Impact

Nags Head, located at the northeastern part of North Carolina in the U.S., has sustained chronic erosion over the past 50 years. In 2005, Coastal Science & Engineering (CSE) was retained by the town of Nags Head to develop an interim beach restoration plan. Profile volume change was used in the planning and preliminary design of the project, and longshore and cross-shore numerical models were used in the final design to refine the preliminary nourishment plan and increase potential longevity of the project. This paper focuses on the key factors of the longshore numerical model setup for the project. These include model selection, input data and parameters, model calibration, and applications under different design alternatives. The Generalized Model for Simulating Shoreline Changes (GENESIS) was used in this study to evaluate shoreline evolution under normal wave conditions during various stages of the design life following the beach nourishment project. The model was used to identify the potential occurrence of erosional hotspots and to optimize the nourishment design so that the effects of such hotspots could be avoided or minimized where possible. Model results were also used to evaluate the impact of borrow area dredging on longshore transport in the project area and the impact of nourishment on shoaling in the adjacent inlet. The project encompasses 10.11 miles (mi) (16.28 kilometers-km) of ocean shoreline, and the design nourishment volume is based on the total permitted volume of 4 million cubic yards (cy) (3 million cubic meters-m³). [Note: As-built length was 10.0 mi and volume was 4.615 million cubic yards.] The final design has fill densities varying from north to south in relation to historical erosion rates and model projections. The average fill density is 75 cubic yards per foot (cy/ft) (188 m³/m) and ranges from 38 cy/ft to 150 cy/ft (95 m³/m to 375 m³/m). In conclusion, it is shown that the numerical model selected in this study was capable of predicting the overall performance of the large scale beach nourishment project in Nags Head as well as the performance at a particular location within or adjacent to the project, and its design methods can offer guidance to future projects.

scholarly journals Charge-Based Continuous Equations for the Transconductance and Output Conductance of Graded-Channel SOI MOSFET’s

2007 ◽  
Vol 2 (2) ◽  
pp. 104-110
Author(s):  
Michelly De Souza ◽  
Marcelo A. Pavanello
Keyword(s):  
Channel Length ◽  
Open Loop ◽  
Silicon On Insulator ◽  
Experimental Results ◽  
Voltage Gain ◽  
Velocity Saturation ◽  
Wide Range ◽  
Carrier Velocity ◽  
Good Agreement ◽  
Output Conductance

This paper presents charge-based continuous equations for the transconductance and output conductance of submicrometer Graded-Channel (GC) Silicon-On-Insulator (SOI) nMOSFET. The effects of carrier velocity saturation, channel length modulation and drain-induced barrier lowering were taken into account in the proposed equations. Experimental results were used to test the validity of the equations by comparing not only the transconductance and the output conductance, but also the Early voltage and the open-loop voltage gain, showing a good agreement in a wide range of bias.

scholarly journals Experimental and FE Study on Impact Strength of Toughened Glass–Retrospective Approach

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7658
Author(s):  
Marcin Kozłowski ◽  
Kinga Zemła ◽  
Magda Kosmal ◽  
Ołeksij Kopyłow
Keyword(s):  
Numerical Models ◽  
Peak Stress ◽  
Impact Loads ◽  
Toughened Glass ◽  
Load Duration ◽  
Wide Range ◽  
Modelling Methodology ◽  
Glass Panels ◽  
Set Up ◽  
The Impact

Due to the high cost of experiments commonly performed to verify the resistance of glass elements to impact loads, numerical models are used as an alternative to physical testing. In these, accurate material parameters are crucial for a realistic prediction of the behaviour of glass panels subjected to impact loads. This applies in particular to the glass’s strength, which is strictly dependent on the strain rate. The article reports the results of an extensive experimental campaign, in which 185 simply supported toughened glass samples were subjected to hard-body impacts. The study covers a wide range of glass thicknesses (from 5 to 15 mm), and it aims to determine a critical drop height causing fracture of the glass. Moreover, a 3D numerical model of the experimental set-up was developed to reproduce the experiments numerically and retrospectively to determine the peak stress in glass that developed during the impact. Based on the results of numerical simulations, a load duration factor of 1.40 for toughened glass for impact loads is proposed. In addition, the paper includes a case study to demonstrate the use of the modelling methodology and results of the work on a practical example of an internal glass partition wall.

scholarly journals KNSwing—On the Mooring Loads of a Ship-Like Wave Energy Converter

2019 ◽  
Vol 7 (2) ◽  
pp. 29
Author(s):  
Kim Nielsen ◽  
Jonas Thomsen
Keyword(s):  
Numerical Model ◽  
Wave Energy ◽  
Numerical Models ◽  
Breaking Waves ◽  
Wave Energy Converter ◽  
Experimental Results ◽  
Irregular Waves ◽  
Mooring System ◽  
Energy Converter ◽  
The Waves

The critical function of keeping a floating Wave Energy Converter in position is done by a mooring system. Several WECs have been lost due to failed moorings, indicating that extreme loads, reliability and durability are very important aspects. An understanding of the interaction between the WEC’s motion in large waves and the maximum mooring loads can be gained by investigating the system at model scale supported by numerical models. This paper describes the testing of a novel attenuator WEC design called KNSwing. It is shaped like a ship facing the waves with its bow, which results in low mooring loads and small motions in most wave conditions when the structure is longer than the waves. The concept is tested using an experimental model at scale 1:80 in regular and irregular waves, moored using rubber bands to simulate synthetic moorings. The experimental results are compared to numerical simulations done using the OrcaFlex software. The experimental results show that the WEC and the mooring system survives well, even under extreme and breaking waves. The numerical model coefficient concerning the nonlinear drag term for the surge motion is validated using decay tests. The numerical results compare well to the experiments and, thereby, the numerical model can be further used to optimize the mooring system.

scholarly journals Dynamic Response of a Single-Layer Reticulated Dome during Aircraft Impact Based on S-J Modeling Method

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Li Lin ◽  
Bo Huang ◽  
Yunhui Sun ◽  
Yu Zhu ◽  
Duozhi Wang
Keyword(s):  
Numerical Model ◽  
Temperature Effect ◽  
Failure Modes ◽  
Numerical Models ◽  
Material Model ◽  
Modeling Method ◽  
Dynamic Responses ◽  
Shell Structures ◽  
Large Strains ◽  
The Impact

In previous numerical models developed for the impact dynamic responses of reticulated domes, mostly BEAM 161 elements and piecewise linear plastic material model have been employed and spherical joints have been simplified as intersection points of beams, which is called the B-P method. The B-P method can be employed in studying the dynamic responses of reticulated shells under low- to moderate-speed impacts with no obvious temperature effect. However, the analysis of the dynamic responses of reticulated shells under moderate- and high-speed impacts of missiles and other aircraft using this method had errors because it could not take into account the temperature effect. To accurately describe the mechanical responses of reticulated shells under aircraft impacts, the Johnson–Cook material model considering temperature effect with corresponding SHELL 163 element was selected for determining the members of the numerical model and the shell element was used to establish the spherical joints of reticulated shells; the whole process was called the S-J modeling method. This modeling method was capable of considering the effects of high strain rates, high temperatures, large strains, stress state change, and loading history. S-J and B-P methods were used to model the reticulated shell structures. Comparing the numerical analysis results of the drop hammer impact of the two developed methods with experimental results verified the accuracy of the S-J modeling method. In addition, based on the results obtained from the S-J modeling method and LS-DYNA finite element analysis software, a numerical model was established for small aircraft impact reticulated shells and the failure modes and dynamic responses of reticulated shell structures under aircraft impacts were studied. In terms of energy analysis, it was found that the effects of roof plates, spherical joints, and temperature softening could not be ignored in such studies.

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