scholarly journals Rate-Dependent Mechanical Behaviour of Semilunar Valves Under Biaxial Deformation: From Quasi-Static to Physiological Loading Rates

2019 ◽  
Author(s):  
Afshin Anssari-Benam ◽  
Yuan-Tsan Tseng ◽  
Gerhard A. Holzapfel ◽  
Andrea Bucchi
Keyword(s):  
Mechanical Behaviour ◽  
Loading Rates ◽  
Semilunar Valves ◽  
Rate Dependent ◽  
Physiological Loading ◽  
Biaxial Deformation

Human Tibial Cartilage Reveals Non-Linear and Non-Uniform Regional Topography Under Physiological Loading Rates

2012 ◽  
Author(s):  
Jessica M. Deneweth ◽  
Kelly E. Newman ◽  
Stephen M. Sylvia ◽  
Scott G. McLean ◽  
Ellen M. Arruda
Keyword(s):  
Mechanical Response ◽  
Critical Role ◽  
Joint Mechanics ◽  
Healthy Human ◽  
Tibial Cartilage ◽  
Loading Rates ◽  
Physiological Loading ◽  
Regional Topography ◽  
Abnormal Pattern

Nearly 3% of individuals worldwide experience pain, immobility, and compromised quality of life due to knee osteoarthritis (OA)1. It has been widely accepted that joint mechanics play a critical role in the initiation and progression of knee OA2. A shift away from the normal joint motion, for example due to injury or malalignment, is believed to produce an abnormal pattern of cartilage loading that creates unusual and damaging stresses within the tissue. Accurate knowledge of cartilage’s normal mechanical response to physiological loading—and particularly the regional dependence of this response—is critical to successfully testing this theory. To our knowledge, little is known about the regionally-dependent mechanical response of healthy human tibial cartilage under physiological loading conditions. There is also a compelling need for more accurate cartilage data to be integrated into computational simulations of the knee joint. Hence, the purpose of this study was two-fold: 1) to characterize the typical stress-strain response of tibial cartilage at 21 locations across the tibial plateau when subjected to loading representative of human walking, and 2) to demonstrate that these 21 sites can be reduced to a small number of regions displaying significantly different average moduli.

scholarly journals Experimental Investigation of Rate-Dependent Inner Hysteresis Loops in PZT

2005 ◽  
Vol 881 ◽  
Author(s):  
Alexander York ◽  
Stefan Seelecke
Keyword(s):  
Experimental Investigation ◽  
Systematic Study ◽  
Domain Switching ◽  
Piezoelectric Materials ◽  
Relaxation Times ◽  
Hysteresis Loops ◽  
Loading Rates ◽  
Rate Dependent ◽  
Realistic Modeling ◽  
Kinetics Of

AbstractThe rate-dependence of piezoelectric materials resulting from the kinetics of domain switching is an important factor that needs to be included in realistic modeling attempts. This paper provides a systematic study of the rate-dependent hysteresis behavior of a commercially available PZT stack actuator. Experiments covering full as well as minor loops are conducted at different loading rates with polarization and strain recorded. In addition, the creep behavior at different constant levels of the electric field is observed. This provides evidence of kinetics being characterized by strongly varying relaxation times that can be associated with different switching mechanisms.

Experimental study on hardening characteristics and loading rate dependent mechanical behaviour of gypsum mixed sand

2020 ◽  
Vol 262 ◽  
pp. 119992 ◽  
Author(s):  
Zain Maqsood ◽  
Junichi Koseki ◽  
Md. Kamrul Ahsan ◽  
Masum Shaikh ◽  
Hiroyuki Kyokawa
Keyword(s):  
Experimental Study ◽  
Mechanical Behaviour ◽  
Loading Rate ◽  
Rate Dependent

Improved Nanoindentation Phase Transformation in Functional Structure of NiTi SMA and Graphene

2015 ◽  
Vol 1119 ◽  
pp. 160-164
Author(s):  
Abbas Amini ◽  
Chun Hui Yang ◽  
Yang Xiang
Keyword(s):  
Indentation Depth ◽  
Loading Rate ◽  
Spherical Indentation ◽  
Niti Shape Memory Alloy ◽  
Cooling Process ◽  
Graphene Layers ◽  
Loading Rates ◽  
Rate Dependent ◽  
Niti Sma ◽  
Superelastic Deformation

Graphene layers were deposited on the surface of NiTi shape memory alloy (SMA) to enhance the spherical indentation depth and the phase transformed volume through an extra nanoscale cooling. The graphene-deposited NiTi SMA showed deeper nanoindentation depths during the solid-state phase transition, especially at the rate dependent loading zone. Larger superelastic deformation confirmed that the nanoscale latent heat transfer through the deposited graphene layers allowed larger phase transformed volume in the bulk and, therefore, more stress relaxation and depth can be achieved. During the indentation loading, the temperature of the phase transformed zone in the stressed bulk increased by ~12-43°C as the loading rate increased from 4,500 μN/s to 30,000 μN/s. The layers of graphene enhanced the cooling process at different loading rates by decreasing the temperature up to ~3-10°C depending on the loading rate.

Characteristics of Adhesive Joints under Rate-Dependent Tensile Loading

2014 ◽  
Vol 660 ◽  
pp. 618-622 ◽  
Author(s):  
Mahzan Johar ◽  
King Jye Wong ◽  
Mohd Nasir Tamin
Keyword(s):  
Tensile Load ◽  
Tensile Loading ◽  
Adhesive Joints ◽  
Optimum Level ◽  
Cohesive Failure ◽  
Pressure Sensitive Adhesive ◽  
Loading Rates ◽  
Rate Dependent ◽  
Pressure Sensitive ◽  
Linear Behavior

Effects of loading rates on deformation and mechanical properties of adhesive joints are examined in this study. For this purpose, acrylic foam pressure sensitive adhesive (PSA) was employed with aluminum adherents. Tensile loading of the adhesive joint was applied at displacement rates ranging from 5 to 500 mm/min. Results show that the tensile load-displacement response is characterized by three regimes, namely an initial non-linear behavior with initiation of cavities, a hardening behavior through fibrillation process and the final fracture of the stretched fibrils. The strengths of the adhesive joints increases asymptotically from 0.56 to 1.92 MPa over the displacement rates from 5 to 500 mm/min. Both modulus and strain energy density at fracture reach optimum level around a displacement rate of 100 mm/min. Adhesive failure of the joint dominates at low loading rate (below 10 mm/min.) while cohesive failure is prominent at faster loading rates above 250 mm/min.

scholarly journals Fasteners in Steel Fiber Reinforced Concrete Subjected to Increased Loading Rates

Fibers ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 93 ◽  
Author(s):  
Boglárka Bokor ◽  
Máté Tóth ◽  
Akanshu Sharma
Keyword(s):  
Reinforced Concrete ◽  
Static Loading ◽  
Steel Fiber ◽  
Plain Concrete ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Loading Rates ◽  
Rate Dependent ◽  
Ultimate Resistance

Increased loading rates on fasteners may be caused by high ground accelerations as a consequence of e.g., nuclear explosions, earthquakes or car collisions. It was concluded by Hoehler et al. (2006) that fasteners under rapid loading rates show an increased ultimate resistance in the concrete dominant failure modes or the ultimate resistance is at least as large as under quasi-static loading. Due to the increased demand on using fasteners in steel fiber reinforced concrete (SFRC), it is intended to show how the ultimate concrete cone capacity of fasteners changes under higher than quasi-static loading rate in normal plain concrete (PC) and in SFRC. This paper presents the results of an extensive experimental program carried out on single fasteners loaded in tension in normal plain concrete and in SFRC. The test series were conducted using a servo-hydraulic loading cylinder. The tests were performed in displacement control with a programmed ramp speed of 1, 100, 1000, and 3500 mm/min. This corresponded to calculated initial loading rates ranging between 0.4 and 1600 kN/s. The results of the tension tests clearly show that the rate-dependent behavior of fasteners in SFRC with 30 and 50 kg/m3 hooked-end-type fibers fits well to the previously reported rate-dependent concrete cone behavior in normal plain concrete. Additionally, a positive influence of the fibers on the concrete cone capacity is clearly visible.

scholarly journals Identification of strain rate-dependent mechanical behaviour of DP600 under in-plane biaxial loadings

2016 ◽  
Vol 676 ◽  
pp. 366-376 ◽  
Author(s):  
Wei Liu ◽  
Dominique Guines ◽  
Lionel Leotoing ◽  
Eric Ragneau
Keyword(s):  
Strain Rate ◽  
Mechanical Behaviour ◽  
Rate Dependent
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