scholarly journals Non‐uniform strain distribution in anterolateral capsule of knee: Implications for surgical repair

2019 ◽  
Vol 37 (5) ◽  
pp. 1025-1032
Author(s):  
Daniel Guenther ◽  
Stephanie L. Sexton ◽  
Kevin M. Bell ◽  
Sebastián Irarrázaval ◽  
Freddie H. Fu ◽  
...  
Keyword(s):  
Strain Distribution ◽  
Surgical Repair ◽  
Uniform Strain ◽  
Anterolateral Capsule

scholarly journals Strain Gage Test Results of Band-Type Locking Rings for a Typical Drum Type Radioactive Material Package

2002 ◽  
Author(s):  
Charles A. McKeel ◽  
Allen C. Smith
Keyword(s):  
Uniform Distribution ◽  
Strain Gage ◽  
Strain Distribution ◽  
Drop Test ◽  
Uniform Strain ◽  
Radioactive Material ◽  
Test Results ◽  
Lower Weight ◽  
Band Type

Band type closure rings are commonly used for securing the drum lid on radioactive material packages of lower weight classifications. Lid installation is achieved by placing the band around the perimeter of the lidded drum and tightening the single bolt in stages until a designated torque value is obtained. The band is subjected to heavy rapping with a soft hammer during installation to equilibrate the band strains around the drum perimeter. The study described here investigated the strain distributions in the band throughout the installation process. The results show that a uniform strain distribution is achieved during installation and that the hammering of the band aids in achieving the uniform distribution. The results of the strain levels after the drop test indicate that the locking rings maintain some pre-tension, even after severe targeted drops that crush a portion of the drum top.

scholarly journals The Influence of the Specimen Shape and Loading Conditions on the Parameter Identification of a Viscoelastic Brain Model

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Costin D. Untaroiu
Keyword(s):  
Parameter Identification ◽  
Strain Distribution ◽  
Nonlinear Behavior ◽  
Relaxation Curve ◽  
Uniform Strain ◽  
High Rate ◽  
Optimization Approach ◽  
Material Models ◽  
Fe Simulations ◽  
Specimen Height

The mechanical properties of brain under various loadings have been reported in the literature over the past 50 years. Step-and-hold tests have often been employed to characterize viscoelastic and nonlinear behavior of brain under high-rate shear deformation; however, the identification of brain material parameters is typically performed by neglecting the initial strain ramp and/or by assuming a uniform strain distribution in the brain samples. Using finite element (FE) simulations of shear tests, this study shows that these simplifications have a significant effect on the identified material properties in the case of cylindrical human brain specimens. Material models optimized using only the stress relaxation curve under predict the shear force during the strain ramp, mainly due to lower values of their instantaneous shear moduli. Similarly, material models optimized using an analytical approach, which assumes a uniform strain distribution, under predict peak shear forces in FE simulations. Reducing the specimen height showed to improve the model prediction, but no improvements were observed for cubic samples with heights similar to cylindrical samples. Models optimized using FE simulations show the closest response to the test data, so a FE-based optimization approach is recommended in future parameter identification studies of brain.

Piezoelectric energy harvesting using L-shaped structures

2017 ◽  
Vol 29 (6) ◽  
pp. 1206-1215 ◽  
Author(s):  
Donghuan Liu ◽  
Mohammed Al-Haik ◽  
Mohamed Zakaria ◽  
Muhammad R Hajj
Keyword(s):  
Energy Harvesting ◽  
Power Density ◽  
Cantilever Beam ◽  
Strain Distribution ◽  
Uniform Strain ◽  
Main Beam ◽  
Piezoelectric Energy Harvesting ◽  
Frequency Range ◽  
Piezoelectric Energy

Energy harvesting from an L-shaped structure, formed by two beams and corner and end masses, is investigated with the objective of expanding the bandwidth of the frequency range over which energy can be harvested. The structure is excited in a direction that yields the most uniform strain distribution along its main beam. The length of the auxiliary beam is varied to determine its effect on the level and breadth of the frequency range over which energy can be harvested. Results from experiments having different geometries are presented and discussed. It is determined that the frequency range over which energy can be harvested from such structures is much larger than levels harvested when using a cantilever beam. The experiments also show that L-shaped structures harvest more power when the length of the auxiliary beam is increased. On the contrary, the power density of the L-shaped structure is much smaller than that of the cantilever beam. The ability to control the bandwidth of frequency over which energy is harvested through proper adjustment of beam lengths is demonstrated.

scholarly journals Simultaneous Measurement of Temperature and Strain Based on Peak Power Changes and Wavelength Shift Using Only One Uniform Fiber Bragg Grating

2021 ◽  
Author(s):  
abdollah malakzadeh ◽  
mohsen mansoursamaei ◽  
Rasoul Pashaie
Keyword(s):  
Fiber Bragg Grating ◽  
Cantilever Beam ◽  
Simultaneous Measurement ◽  
Strain Distribution ◽  
Peak Power ◽  
Quadratic Function ◽  
Uniform Strain ◽  
Bragg Grating ◽  
Wavelength Shift ◽  
Bragg Wavelength

Abstract Many efforts have been devoted to simultaneous measurements of strain and temperature by FBG sensors and several improving techniques have been resulted and implemented on the measurement. Most of them are based on two or more FBGs configurations or a single non-uniform FBG implementation. We propose simultaneous measurement of temperature and strain based on peak power changes and Bragg wavelength shifts using only one uniform fiber Bragg grating (FBG). We placed a ramp with the angle of θ, similar to a tilted cantilever beam, on an assumptive structure and stuck a uniform FBG on it. When a uniform strain applied to a structure, the cantilever beam converts it to a non-uniform strain distribution along with itself and consequently the uniform FBG. By creating this non-uniform strain distribution, the peak power of the reflection spectrum of the FBG will be sensitive to strain changes. In addition, the Bragg wavelength shift will be sensitive to both temperature and strain parameters. According to our simulation, temperature sensitivity of 14.15 pm/℃ is obtained for FBG sensor without any changes in the peak power. The strain sensitivity of 0.7837 pm/µε, and a nonlinear sensitivity according to a quadratic function for peak power variation are also observed.

Piezoelectric Compliant Mechanism Energy Harvesters Excited Under Large Base Accelerations

2016 ◽  
Author(s):  
Xiaokun Ma ◽  
Susan Trolier-McKinstry ◽  
Christopher D. Rahn
Keyword(s):  
Strain Distribution ◽  
Energy Harvester ◽  
Compliant Mechanism ◽  
Average Power ◽  
Low Frequency ◽  
Uniform Strain ◽  
Bridge Structure ◽  
Energy Harvesters ◽  
Axial Stretching ◽  
Stretching Effect

A piezoelectric compliant mechanism (PCM) energy harvester is designed, modeled, and analyzed that consists of a polyvinylidene diflouoride, PVDF unimorph clamped at its base and attached to a compliant mechanism at its tip. The compliant hinge stiffness is carefully tuned to approach a low frequency first mode with an efficient (nearly quadratic) shape that provides a uniform strain distribution. A nonlinear model of the PCM energy harvester under large base excitation is derived to determine the maximum power that can be generated by the device. Simulation results show that the PCM bridge structure self-limits the displacement and maximum strain at large excitations compared with the proof mass cantilever, improving the device robustness. The PCM outperforms the cantilever in both average power and power-strain sensitivity at high accelerations due to the PCM axial stretching effect and its more uniform strain distribution.

On the non-uniform strain distribution along the length of stress fibers

2020 ◽  
Vol 2020.95 (0) ◽  
pp. 04_401
Author(s):  
Tatsuki OKAMOTO ◽  
Tsubasa S. MATSUI ◽  
Shinji DEGUCHI
Keyword(s):  
Strain Distribution ◽  
Uniform Strain ◽  
Stress Fibers
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