scholarly journals Rate-dependence of ‘wet’ biological adhesives and the function of the pad secretion in insects

Soft Matter ◽  
2015 ◽  
Vol 11 (44) ◽  
pp. 8661-8673 ◽  
Author(s):  
David Labonte ◽  
Walter Federle
Keyword(s):  
Energy Dissipation ◽  
Fracture Mechanics ◽  
Theoretical Approach ◽  
Rate Dependence ◽  
Force Measurements ◽  
Biological Adhesives

We combine detailed force measurements on isolated attachment organs of live insects with a theoretical approach based on fracture mechanics to show that viscous energy dissipation of ‘wet’ insect pads is akin to that of ‘dry’ elastomers.

Delamination modelling of a curved composite beam subjected to an opening bending moment

2003 ◽  
Vol 38 (5) ◽  
pp. 453-457 ◽  
Author(s):  
W Wang ◽  
R. A Shenoi
Keyword(s):  
Fracture Mechanics ◽  
General Solution ◽  
Critical Load ◽  
Theoretical Approach ◽  
Composite Beam ◽  
Beam Theory ◽  
Bending Moment ◽  
Radius Of Curvature ◽  
Curved Beam ◽  
Mechanics Concepts

A theoretical approach is developed for the case of delamination of a curved composite beam under an opening bending moment. This is based on linear curved beam theory coupled with fracture mechanics concepts. The general solution is applied to analyse a specific case of delamination occurring at the mid-plane. The effects of the arc angle of delamination crack and the radius of curvature of the beam on the critical load are also studied.

scholarly journals Virial and Energy Dissipation in Measurement of Dynamic Acoustic Forces Using Bimodal-frequency Excitation of Micro-cantilever Array

2021 ◽  
Vol 4 (1) ◽  
pp. 332-340
Author(s):  
Cagri Yilmaz ◽  
Eyup Sabri Topal
Keyword(s):  
Energy Dissipation ◽  
High Sensitivity ◽  
Mathematical Framework ◽  
Force Frequency ◽  
Force Measurements ◽  
Excitation Scheme ◽  
Frequency Bands ◽  
Cantilever Array ◽  
Frequency Excitation ◽  
Micro Cantilever

Virial and energy dissipation, related to oscillation observable responses, possess complementary information regarding acoustic force measurements. In this paper, we introduce a mathematical framework describing the analytic relationship between oscillation observables and energy quantities at the second eigenmode in the measurement of dynamic acoustic forces. We utilize a bimodal-frequency excitation scheme for actuation of the micro-cantilever array to obtain high-sensitivity frequency bands. Herein, we analyze the virials of acoustic force interaction and the energy dissipation levels on the domain of acoustic force frequency. For our case, we obtain the high-frequency bands of around 200-270 kHz and 440-570 kHz for the force strengths in the range of 4.0-36.0 pN. In addition, results of virials and dissipated power with respect to acoustic force strengths are introduced for low- and high-sensitivity frequency regions. Therefore, the energy quantities can be robustly utilized to determine high-sensitivity frequency windows in the measurement of dynamic acoustic forces.

On the Puncture Mechanics of Rubber

1994 ◽  
Vol 67 (5) ◽  
pp. 743-760 ◽  
Author(s):  
A. Stevenson ◽  
Kamarudin Ab Malek
Keyword(s):  
Fracture Mechanics ◽  
Elasticity Theory ◽  
Theoretical Approach ◽  
Elastic Energy ◽  
Model Experiment ◽  
Crack Formation ◽  
Biaxial Stretching ◽  
Rubber Surface ◽  
Tearing Energy ◽  
Ring Crack

Abstract The mechanics of puncture have been studied experimentally and theoretically, by means of fracture mechanics. When a sharp cylindrical indentor penetrates rubber, a starter crack initiates as a ring on the rubber surface before puncture occurs. By treating this as militating puncture, an equation has been derived for the energy of puncture. The elastic energy stored in the rubber is considered in terms of the energy beneath and surrounding the indentor. An equation for the energy beneath the indentor is determined with the aid of a model experiment based on the biaxial stretching of rubber by inflation. The energy stored in the rubber surrounding the indentor is calculated using elasticity theory. The magnitude of these contributions is assessed for different indentor sizes and different rubber vulcanizates, The theoretical approach is shown to be verified by a series of experiment for sharp indentors. The values of puncture energy so obtained were found to agree well with the catastrophic tearing energy obtained from trouser tear tests. For blunt indentors which do not cause ring crack formation, other considerations are needed. These are discussed together with experimental results for hemispherical indentors.

Mechanics of Modulation Assisted Machining

2013 ◽  
Author(s):  
Ho Yeung ◽  
Yang Guo ◽  
Narayan K. Sundaram ◽  
James B. Mann ◽  
W. Dale Compton ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Specific Energy ◽  
Frequency Modulation ◽  
Chip Formation ◽  
Low Frequency ◽  
Contact Condition ◽  
Force Measurements

The controlled application of low-frequency modulation to machining — Modulation Assisted Machining (MAM) — effects discrete chip formation and disrupts the severe contact condition at the tool-chip interface. The role of modulation in reducing the specific energy of machining with ductile alloys is demonstrated using direct force measurements. The observed changes in energy dissipation are analyzed and explained, based on the mechanics of chip formation.

Differential polarization imaging of sickled cells

1988 ◽  
Vol 46 ◽  
pp. 62-63
Author(s):  
Marcos F. Maestre
Keyword(s):  
Optical Properties ◽  
Theoretical Approach ◽  
Polarized Light ◽  
Polarization Microscopy ◽  
Spectroscopic Techniques ◽  
Polarization Imaging ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Microscopic Scale ◽  
Chiral Structures

Recently we have developed a form of polarization microscopy that forms images using optical properties that have previously been limited to macroscopic samples. This has given us a new window into the distribution of structure on a microscopic scale. We have coined the name differential polarization microscopy to identify the images obtained that are due to certain polarization dependent effects. Differential polarization microscopy has its origins in various spectroscopic techniques that have been used to study longer range structures in solution as well as solids. The differential scattering of circularly polarized light has been shown to be dependent on the long range chiral order, both theoretically and experimentally. The same theoretical approach was used to show that images due to differential scattering of circularly polarized light will give images dependent on chiral structures. With large helices (greater than the wavelength of light) the pitch and radius of the helix could be measured directly from these images.

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