Correlating Drop Impact Simulations With Drop Impact Testing Using High-Speed Camera Measurements

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
J. J. M. Zaal ◽  
W. D. van Driel ◽  
F. J. H. G. Kessels ◽  
G. Q. Zhang
Keyword(s):  
High Speed ◽  
Simulation Models ◽  
3D Models ◽  
Drop Impact ◽  
Impact Testing ◽  
Navigation Systems ◽  
High Speed Camera ◽  
Impact Performance ◽  
Impact Simulations ◽  
Board Level

The increased use of mobile appliances such as mobile phones and navigation systems in today’s society has resulted in an increase in reliability issues related to drop performance. Mobile appliances are dropped several times during their lifespan and the product is required to survive common drop accidents. A widely accepted method to assess the drop reliability of microelectronics on board-level is the drop impact test. This test has been standardized by international councils such as Joint Electron Device Engineering Council and is widely adopted throughout the industry. In this research the solder loading is investigated by combining high-speed camera measurements of several drop impact tests with verified finite element models. These simulation models are developed in order to gain an insight on the loading pattern of solder joints based on interconnect layout, drop conditions, and product specifications prior to physical prototyping. Deflections and frequencies during drop testing are measured using a high-speed camera setup. The high-speed camera experiments are performed on two levels: machine level (rebounds with and without a catcher) and product level (with different levels of energy and different pulse times). Parametric (dynamic and quasistatic) 3D models are developed to predict the drop impact performance. The experimental results are used to verify and enhance the simulation models, e.g., by tuning the damping parameters. As a result, the verified models can be used to determine the location of the critical solder joint and to obtain estimates of the solder lifetime performance.

Development of high speed board level bend tester for drop impact applications

2009 ◽  
Author(s):  
Shu Min Lim ◽  
Zhong Chen ◽  
Hun Shen Ng ◽  
Tong Yan Tee ◽  
Choong Peng Khoo ◽  
...  
Keyword(s):  
High Speed ◽  
Drop Impact ◽  
Board Level

A Comprehensive Review of Drop Impact Modeling on Portable Electronic Devices

2011 ◽  
Vol 64 (2) ◽  
Author(s):  
Y. H. Yau ◽  
Shijie Norman Hua
Keyword(s):  
Impact Analysis ◽  
Electronic Devices ◽  
Time Frame ◽  
Drop Impact ◽  
Current Status ◽  
Impact Performance ◽  
The Past ◽  
Comprehensive Survey ◽  
Board Level ◽  
Future Work

This article is dedicated to the review of publications on drop impact analysis performed on consumer electronic devices such as cellular phones and two-way radios in the past decade. Prior to the highlights of this review, the scope and motivation behind this work will be briefly explained. A comprehensive survey on published literatures devoted to the methodologies established to analyze the reliability of electronic products exposed to the event of drop impact is presented. The scope of the review is extended beyond product level analysis to also include drop impact study at board level. This type of review is novel and has not been published in the past. The focus will be on the different analytical and numerical modeling approaches and the current status of finite element method in predicting the drop impact performance of electronic devices. Of equal interest is the methodology adopted in past work to establish a correlation between numerical and experimental results. This article serves as a reference to all intended future work which could be an extension from the current known art of drop impact analysis on electronic devices. The time frame of this review is up to year 2010.

The use of high-speed camera technique for observation of soil splash phenomena

2020 ◽  
Author(s):  
Michał Beczek ◽  
Magdalena Ryżak ◽  
Rafał Mazur ◽  
Agata Sochan ◽  
Cezary Polakowski ◽  
...  
Keyword(s):  
High Speed ◽  
Initial Moisture Content ◽  
Soil Surface ◽  
Drop Impact ◽  
Solid Particles ◽  
High Speed Camera ◽  
Water Drops ◽  
Crown Formation ◽  
Raindrop Splash ◽  
The Impact

<p>Soil, i.e. the natural outer layer of the lithosphere and an important component of many ecosystems, may be subjected to various degradation processes dependent on different factors. One of the forms of degradation is water erosion, where the first stage is the splash phenomenon. This process is caused by water drops hitting the soil surface during rainfall, which results in detachment and ejection of splashed material and transport thereof over different distances. The aim of this study was to present the application of the high-speed camera technique for investigations of surface phenomena (effects) influenced by the impact of a single water-drop onto the soil surface.</p><p>The measurements were conducted on types of soil differentiated in terms of texture and variants of initial moisture content, which helped to observe different aspects of the soil splash phenomenon. Water drops with a diameter of 4.2 mm fell on soil samples with various kinetic energy values depending on the height of the drop fall (up to 7m). Phantom Miro M310 high-speed cameras were used to observe the effects of the drop impact. The devices registered images with a speed of 3260 fps (frames per second) at the highest available resolution (1280x800 pixels). The following phenomena were observed: I) ejection of splashed particles (including solid soil particles, water droplets, solid particles within the water sheath); II) crown formation – when the drop impacting onto wet soil surface forces the liquid layer to rise up and form a crown (important for the mode and amount of transferred material); III) micro-crater formation – the deformation of the surface and formation of a shallow pool after the drop impact.          </p><p> </p><p>This work was partly financed from the National Science Centre, Poland; project no. 2018/31/N/ST10/01757.</p><p> </p><p>References:</p><ol><li>Beczek M., Ryżak M., Sochan A., Mazur R., Bieganowski A.: The mass ratio of splashed particles during raindrop splash phenomenon on soil surface. GEODERMA 347, 40-48, 2019</li> <li>Beczek M., Ryżak M., Lamorski K., Sochan A., Mazur R., Bieganowski A.: Application of X-ray computed microtomography to soil craters formed by raindrop splash. Geomorphology 303, 357-361, 2018</li> <li>Beczek M., Ryżak M., Sochan A., Mazur R., Polakowski C., Bieganowski A.: The differences in crown formation during the splash on the thin water layers formed on the saturated soil surface and model surface. PLoS ONE 12, 2017</li> </ol>

Aerodynamic and aeroacoustic performance investigations on modified H-rotor Darrieus wind turbine

2021 ◽  
pp. 0309524X2110039
Author(s):  
Amgad Dessoky ◽  
Thorsten Lutz ◽  
Ewald Krämer
Keyword(s):  
Wind Turbine ◽  
High Speed ◽  
Cfd Simulation ◽  
Vertical Axis ◽  
3D Models ◽  
Power Coefficient ◽  
Design Parameters ◽  
Second Phase ◽  
Vertical Axis Wind Turbine ◽  
Guide Vanes

The present paper investigates the aerodynamic and aeroacoustic characteristics of the H-rotor Darrieus vertical axis wind turbine (VAWT) combined with very promising energy conversion and steering technology; a fixed guide-vanes. The main scope of the current work is to enhance the aerodynamic performance and assess the noise production accomplished with such enhancement. The studies are carried out in two phases; the first phase is a parametric 2D CFD simulation employing the unsteady Reynolds-averaged Navier-Stokes (URANS) approach to optimize the design parameters of the guide-vanes. The second phase is a 3D CFD simulation of the full turbine using a higher-order numerical scheme and a hybrid RANS/LES (DDES) method. The guide-vanes show a superior power augmentation, about 42% increase in the power coefficient at λ = 2.75, with a slightly noisy operation and completely change the signal directivity. A remarkable difference in power coefficient is observed between 2D and 3D models at the high-speed ratios stems from the 3D effect. As a result, a 3D simulation of the capped Darrieus turbine is carried out, and then a noise assessment of such configuration is assessed. The results show a 20% increase in power coefficient by using the cap, without significant change in the noise signal.

scholarly journals Tracking by Deblatting

2021 ◽  
Author(s):  
Denys Rozumnyi ◽  
Jan Kotera ◽  
Filip Šroubek ◽  
Jiří Matas
Keyword(s):  
High Speed ◽  
High Performance ◽  
Motion Blur ◽  
Velocity Estimation ◽  
High Speed Camera ◽  
Trajectory Function ◽  
Novel Approach ◽  
Blind Deblurring ◽  
Object Trajectories ◽  
Complex Trajectories

AbstractObjects moving at high speed along complex trajectories often appear in videos, especially videos of sports. Such objects travel a considerable distance during exposure time of a single frame, and therefore, their position in the frame is not well defined. They appear as semi-transparent streaks due to the motion blur and cannot be reliably tracked by general trackers. We propose a novel approach called Tracking by Deblatting based on the observation that motion blur is directly related to the intra-frame trajectory of an object. Blur is estimated by solving two intertwined inverse problems, blind deblurring and image matting, which we call deblatting. By postprocessing, non-causal Tracking by Deblatting estimates continuous, complete, and accurate object trajectories for the whole sequence. Tracked objects are precisely localized with higher temporal resolution than by conventional trackers. Energy minimization by dynamic programming is used to detect abrupt changes of motion, called bounces. High-order polynomials are then fitted to smooth trajectory segments between bounces. The output is a continuous trajectory function that assigns location for every real-valued time stamp from zero to the number of frames. The proposed algorithm was evaluated on a newly created dataset of videos from a high-speed camera using a novel Trajectory-IoU metric that generalizes the traditional Intersection over Union and measures the accuracy of the intra-frame trajectory. The proposed method outperforms the baselines both in recall and trajectory accuracy. Additionally, we show that from the trajectory function precise physical calculations are possible, such as radius, gravity, and sub-frame object velocity. Velocity estimation is compared to the high-speed camera measurements and radars. Results show high performance of the proposed method in terms of Trajectory-IoU, recall, and velocity estimation.

Influence of Main Swirler Vane Angle on the Ignition Performance of TeLESS-II Combustor

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Bo Wang ◽  
Chi Zhang ◽  
Yuzhen Lin ◽  
Xin Hui ◽  
Jibao Li
Keyword(s):  
High Speed ◽  
Inlet Temperature ◽  
Main Stage ◽  
Ignition Process ◽  
High Speed Camera ◽  
Fuel Distribution ◽  
Fuel Droplets ◽  
Planar Laser ◽  
Cfd Method ◽  
Vane Angle

In order to balance the low emission and wide stabilization for lean premixed prevaporized (LPP) combustion, the centrally staged layout is preferred in advanced aero-engine combustors. However, compared with the conventional combustor, it is more difficult for the centrally staged combustor to light up as the main stage air layer will prevent the pilot fuel droplets arriving at igniter tip. The goal of the present paper is to study the effect of the main stage air on the ignition of the centrally staged combustor. Two cases of the main swirler vane angle of the TeLESS-II combustor, 20 deg and 30 deg are researched. The ignition results at room inlet temperature and pressure show that the ignition performance of the 30 deg vane angle case is better than that of the 20 deg vane angle case. High-speed camera, planar laser induced fluorescence (PLIF), and computational fluids dynamics (CFD) are used to better understand the ignition results. The high-speed camera has recorded the ignition process, indicated that an initial kernel forms just adjacent the liner wall after the igniter is turned on, the kernel propagates along the radial direction to the combustor center and begins to grow into a big flame, and then it spreads to the exit of the pilot stage, and eventually stabilizes the flame. CFD of the cold flow field coupled with spray field is conducted. A verification of the CFD method has been applied with PLIF measurement, and the simulation results can qualitatively represent the experimental data in terms of fuel distribution. The CFD results show that the radial dimensions of the primary recirculation zone of the two cases are very similar, and the dominant cause of the different ignition results is the vapor distribution of the fuel. The concentration of kerosene vapor of the 30 deg vane angle case is much larger than that of the 20 deg vane angle case close to the igniter tip and along the propagation route of the kernel, therefore, the 30 deg vane angle case has a better ignition performance. For the consideration of the ignition performance, a larger main swirler vane angle of 30 deg is suggested for the better fuel distribution when designing a centrally staged combustor.

Sign in / Sign up

Export Citation Format

Share Document