A simple hydrodynamic model for the strain field produced in a target by the penetration of a high speed long rod projectile

Observation of damage evolution is of great importance to the understanding of the failure process of rock materials. High-speed DIC system is constructed and used to observe the strain field evolution of the granodiorite disc in Brazilian test. The strain fields at different load levels are analyzed based on the stain abnormality indicator (SAI) which is the ratio of the strain measured in experiment to the strain from theoretical solution in an isotropy and elastic model. SAI could be used to indicate the damage in the specimen. The process of damage and failure of the specimen in Brazilian disc test is quantitatively analyzed and deeply discussed according to the strain fields and the statistics of SAI. Experimental results in this paper show that the failure process of the disc specimen in Brazilian test is not simple crack propagation under tensile load, but a complicated damage evolution procedure.

Download Full-text

Study on Displacement Measurement for Induced Strain Field Based on Digital Speckle Pattern Interferometry Method

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.273.510 ◽

2013 ◽

Vol 273 ◽

pp. 510-514

Author(s):

Jing Liu ◽

Hui Zhang ◽

Jun Li ◽

Da Chuan Chen ◽

Yan Kun Tang

Keyword(s):

Strain Field ◽

High Speed ◽

Speckle Pattern ◽

Measuring Method ◽

Full Field ◽

Digital Speckle Pattern Interferometry ◽

Level Measurement ◽

On Line ◽

Interferometry Method ◽

Digital Speckle

Digital Speckle Pattern Interferometry ( DSPI for short ) method has become one of the most practical worthy techniques for speckle measuring methods with the high-speed development of optic-electronical technique, image processing technology and electronic computer technology. There is a lot of advantages about it, such as uncomplicated operation, non-contacting, advanced automatic level, measurement on-line and extensive using. In this thesis, the displacement variation of the induced strain field for driving by piezoelectric ceramics can be measured by using this method. Thus we can come to a conclusion that digital speckle pattern interferometry is a new measuring method for extracting small-signal. It also provides a powerfully theoretical and experimental platform for study of automated, full-field, high-precision and nondestructive measurement.

Download Full-text

Strain Field Reconstruction of High-speed Train Crossbeam Based on FBG Sensing Network and Load-Strain Linear Superposition Algorithm

IEEE Sensors Journal ◽

10.1109/jsen.2021.3139648 ◽

2021 ◽

pp. 1-1

Author(s):

Zhaohua Li ◽

Yangyang Cheng ◽

Lei Zhang ◽

Guangjun Wang ◽

Zengye Ju ◽

...

Keyword(s):

Strain Field ◽

High Speed ◽

High Speed Train ◽

Linear Superposition ◽

Field Reconstruction

Download Full-text

Axial Strain Measurements in Skeletal Muscle at Various Strain Rates

Journal of Biomechanical Engineering ◽

10.1115/1.2794179 ◽

1995 ◽

Vol 117 (3) ◽

pp. 262-265 ◽

Cited By ~ 33

Author(s):

T. M. Best ◽

J. H. McElhaney ◽

W. E. Garrett ◽

B. S. Myers

Keyword(s):

Skeletal Muscle ◽

Strain Field ◽

High Speed ◽

Soft Tissues ◽

Axial Strain ◽

Local Strain ◽

Optical Systems ◽

Rate Dependent ◽

Strain Formulation ◽

Tissue Deformations

A noncontact optical system using high speed image analysis to measure local tissue deformations and axial strains along skeletal muscle is described. The spatial resolution of the system was 20 pixels/cm and the accuracy was ±0.125mm. In order to minimize the error associated with discrete data used to characterize a continuous strain field, the displacement data were fitted with a third order polynomial and the fitted data differentiated to measure surface strains using a Lagrangian finite strain formulation. The distribution of axial strain along the muscle-tendon unit was nonuniform and rate dependent. Despite a variation in local strain distribution with strain rate, the maximum axial strain, Exx = 0.614 ± 0.045 mm/mm, was rate insensitive and occurred at the failure site for all tests. The frequency response of the video system (1000 Hz) and the measurement of a continuous strain field along the entire length of the structure improve upon previous noncontact optical systems for measurement of surface strains in soft tissues.

Download Full-text

Simulation of the Temperature, Stress, Strain Field in Aluminum Thin-Gauge High-Speed Casting

Materials Science Forum ◽

10.4028/www.scientific.net/msf.704-705.58 ◽

2011 ◽

Vol 704-705 ◽

pp. 58-62

Author(s):

Xiao Bo Liu ◽

Dun Sheng Wu

Keyword(s):

Thermal Stress ◽

Strain Field ◽

High Speed ◽

Coupling Model ◽

Aluminum Melt ◽

Roll Casting ◽

Thermal Stress Field ◽

High Speed Casting ◽

Twin Roll ◽

Melt Solidification

Based on the analyses of aluminum melt solidification and heat transfer during the process of twin-roll casting, a coupling mathematical model of thin-gauge high-speed casting was developed, which included the casting roller shell. At the same time, FEM was adopted to solve the coupling model. The temperature field, thermal stress field and strain field of aluminum melt in casting zone were simulated by this model. When the casting velocity is 7m/min, and the thickness of strip is 2 mm, in the melt zone, the temperature of melt decreases rapidly as it approaches the rollers; the surface stress of strip is larger than the central stress; In the liquid zone and mushy zone, thermal stress is relatively small; in rolling zone, thermal stress is much larger than in the former two zones, and gradually increases along exports, then gradually decreases after the peak; the outsurface strain of the casting strip is larger than the inner strain, and the thermal stress gradually increases along exports.

Download Full-text

A Review of Hydrodynamic Design Methods for Seaplanes

Journal of Ship Production and Design ◽

10.5957/jspd.11180039 ◽

2021 ◽

pp. 1-22

Author(s):

Michael G. Morabito

Keyword(s):

Hydrodynamic Model ◽

High Speed ◽

Early Stage ◽

Model Testing ◽

Naval Academy ◽

Testing Procedures ◽

Testing Facility ◽

Starting Point ◽

Successful Series ◽

Prediction Techniques

The design of successful water-based aircraft requires a close collaboration between the aeronautical engineers and naval architects, who perform high-speed towing tests, stability calculations, or computational fluid dynamics in support of the design. This article presents the fundamental design considerations of waterborne aircraft, which are outside of the typical educational scope of most naval architects, but which they are sometimes asked to address. These include 1) the hydrostatic and hydrodynamic problems associated with seaplane design, 2) early-stage methods for sizing the hull, 3) prediction techniques using archival data, and 4) hydrodynamic model testing procedures. Although a new design will often require substantial iteration to achieve the desired outcome, the information in this article will assist in developing a reasonable starting point for the design spiral and provides sufficient details for a hydrodynamic model testing facility to perform a successful series of model tests on the design. Although much of the work in this field dates from the 1940s, it is important to review this material in light of the current practices being used at hydrodynamic research facilities today. A detailed description of the model testing apparatus and procedure, used in a recent study at the U.S. Naval Academy, is presented to demonstrate the current applicability of these methods and some pitfalls that can be expected in testing.

Download Full-text

Combined nonlocal hydrodynamic model of high-speed penetration of metal jets into high-strength barriers

Technical Physics ◽

10.1134/s1063784214010162 ◽

2014 ◽

Vol 59 (1) ◽

pp. 36-41 ◽

Cited By ~ 3

Author(s):

G. G. Savenkov ◽

T. A. Khantuleva

Keyword(s):

Hydrodynamic Model ◽

High Speed ◽

High Strength

Download Full-text

Deformation and Fracture Failure of a High-Speed Long Rod Intercepted by Linear Explosively Formed Penetrators Sequence

Materials ◽

10.3390/ma13225086 ◽

2020 ◽

Vol 13 (22) ◽

pp. 5086

Author(s):

Yishu Li ◽

Zhonghua Huang ◽

Anshun Shi ◽

Xiangqun Xu ◽

Sanmin Shen ◽

...

Keyword(s):

High Speed ◽

Center Of Mass ◽

Movement Pattern ◽

Difficult Problem ◽

Tungsten Alloy ◽

Low Velocity ◽

Penetration Effect ◽

Fracture Failure ◽

Deformation And Fracture ◽

Long Rod

The fracture failure of a high-speed long rod has historically been a challenge. Since the flying plate and flying rod have a relatively low velocity, it is challenging to achieve a multi-stage fracture of the high-speed long rod within the range of existing technology. In this paper, the linear explosively formed penetrators (LEFPs) sequence with a stable flight velocity of 850 m/s were used to cut a high-speed long rod. We investigated the deformation and fracture of Φ10 mm tungsten alloy long rods having different length-diameter ratios (20, 26, 35) and different speeds (1200, 1400, 1600 m/s) by employing the LEFPs sequence with different spacings (0–40 mm) and different interception angles (30°, 60°). In the meantime, the fractured rods movement pattern was recorded with a high-speed camera to elucidate the change law of the length, speed, linear momentum, and angular momentum of fractured rods. It was found that the length loss rate of the fractured rods is as high as 27%. The fractured rods rotated around the center of mass, and the vertical speed change could reach up to 18% of the muzzle velocity of the long rod, and the greatest reduction of horizontal speed and momentum could reach 37%. The longer the interaction time between LEFPs sequence and the long rod, the more beneficial the failure of the long rod. The application of LEFPs sequence solved the difficult problem of disabling the high-speed long rod, and the quantitative analysis of the fracture failure of the long rod had an important sense for studying the terminal penetration effect of the fractured rods.

Download Full-text