An analysis of the effects of depth-dependent aggregate modulus on articular cartilage stress-relaxation behavior in compression

Osteoarthritis (OA) is a common joint disorder found mostly in elderly people. The role of mechanical behavior in the progression of OA is complex and remains unclear. The stress-relaxation behavior of human articular cartilage in clinically defined osteoarthritic stages may have importance in diagnosis and prognosis of OA. In this study we investigated differences in the biomechanical responses among human cartilage of ICRS grades I, II and III using polymer dynamics theory. We collected 24 explants of human articular cartilage (eight each of ICRS grade I, II and III) and acquired stress-relaxation data applying a continuous load on the articular surface of each cartilage explant for 1180 s. We observed a significant decrease in Young’s modulus, stress-relaxation time, and stretching exponent in advanced stages of OA (ICRS grade III). The stretch exponential model indicated that significant loss in hyaluronic acid polymer might be the reason for the loss of proteoglycan in advanced OA. This work encourages further biomechanical modelling of osteoarthritic cartilage utilizing these data as input parameters to enhance the fidelity of computational models aimed at revealing how mechanical behaviors play a role in pathogenesis of OA.

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Synchronized Heterogeneous Indentation and Stress Relaxation Behavior of Articular Cartilage Upon Macroscopic Compression: A Preliminary Study

Volume 10: Micro- and Nano-Systems Engineering and Packaging ◽

10.1115/imece2014-37060 ◽

2014 ◽

Author(s):

Jiayue Shen ◽

Wenting Gu ◽

Xavier-lewis Palmer ◽

Siqi Guo ◽

Zhili Hao

Keyword(s):

Articular Cartilage ◽

Stress Relaxation ◽

Viscoelastic Behavior ◽

Relaxation Modulus ◽

Relaxation Behavior ◽

Indentation Modulus ◽

Cartilage Sample ◽

Stress Relaxation Behavior ◽

Bovine Articular Cartilage ◽

Preliminary Study

By using a newly-developed experimental technique that is enabled by a polymer-based microfluidic device for detecting distributed normal loads, a preliminary study is presented on the synchronized heterogeneous indentation and stress relaxation behavior of articular cartilage upon macroscopic compression. In a measurement, a rigid cylinder probe is employed to exert macroscopic indentation or step input to a cartilage sample on the device. Consequently, the synchronized heterogeneous viscoelastic behavior of the sample translates to distributed normal loads acting on the device and is captured by the device. While the macroscopic load acting on a sample is recorded by a load cell, the deflections of a sample along its length are captured by the device. Thus, the measured results essentially are the load-deflection relations of a sample along its length. Full-thickness lapine and bovine articular cartilage samples are prepared and measured. A thorough data analysis is implemented on the recorded data for extracting their instant and relaxed indentation modulus, as well as Young’s relaxation modulus.

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Change in intragranular misorientation during stress relaxation behavior in Cu-Ni-Si alloy subjected to continuous cyclic bending

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/1121/1/012030 ◽

2021 ◽

Vol 1121 (1) ◽

pp. 012030

Author(s):

Tatsuya Fukutomi ◽

Narumi Komei ◽

Yoshimasa Takayama ◽

Hideo Watanabe

Keyword(s):

Stress Relaxation ◽

Relaxation Behavior ◽

Stress Relaxation Behavior ◽

Cyclic Bending

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Effects of accelerator type on stress relaxation behavior and network structure of aged natural rubber/chloroprene rubber vulcanizates

Journal of Elastomers & Plastics ◽

10.1177/0095244316663268 ◽

2016 ◽

Vol 49 (5) ◽

pp. 381-396 ◽

Cited By ~ 7

Author(s):

Farzad A Nobari Azar ◽

Murat Şen

Keyword(s):

Stress Relaxation ◽

Natural Rubber ◽

Network Structure ◽

Structural Changes ◽

Relaxation Behavior ◽

Stress Relaxation Behavior ◽

Rubber Blends ◽

Chloroprene Rubber ◽

Weather Changes ◽

Behavior Network

Natural rubber/chloroprene rubber (NR/CR) blends are among the commonly used rubber blends in industry and continuously are exposed to severe weather changes. To investigate the effects of accelerator type on the network structure and stress relaxation of unaged and aged NR/CE vulcanizates, tetramethyl thiuram disulfide, 2-mercaptobenzothiazole, and diphenyl guanidine accelerators have been chosen to represent fast, moderate, and slow accelerator groups, respectively. Three batches have been prepared with exactly the same components and mixing conditions differing only in accelerator type. Temperatures scanning stress relaxation and pulse nuclear magnetic resonance techniques have been used to reveal the structural changes of differently accelerated rubber blends before and after weathering. Nonoxidative thermal decomposition analyses have been carried out using a thermogravimetric analyzer. Results indicate that there is a strong interdependence between accelerator type and stress relaxation behavior, network structure, cross-linking density, and aging behavior of the blends. Accelerator type also affects decomposition energy of the blends.

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