Constitutive models and failure properties of fibrous tissues of carotid artery atheroma based on their uniaxial testing

The mechanical properties of the skin are important for various applications. Numerous tests have been conducted to characterize the mechanical behavior of this tissue, and this article presents a review on different experimental methods used. A discussion on the general mechanical behavior of the skin, including nonlinearity, viscoelasticity, anisotropy, loading history dependency, failure properties, and aging effects, is presented. Finally, commonly used constitutive models for simulating the mechanical response of skin are discussed in the context of representing the empirically observed behavior.

Download Full-text

A Uniaxial Testing Approach for Consistent Failure in Vascular Tissues

Journal of Biomechanical Engineering ◽

10.1115/1.4039577 ◽

2018 ◽

Vol 140 (6) ◽

Cited By ~ 6

Author(s):

Chao Sang ◽

Spandan Maiti ◽

Ronald N. Fortunato ◽

Julia Kofler ◽

Anne M. Robertson

Keyword(s):

Vascular Tissue ◽

Failure Process ◽

Quantitative Information ◽

Uniaxial Tensile ◽

Older Individuals ◽

Uniaxial Tensile Testing ◽

Uniaxial Testing ◽

Failure Properties ◽

Failure Location ◽

Specimen Shape

Although uniaxial tensile testing is commonly used to evaluate failure properties of vascular tissue, there is no established protocol for specimen shape or gripping method. Large percentages of specimens are reported to fail near the clamp and can potentially confound the studies, or, if discarded will result in sample waste. The objective of this study is to identify sample geometry and clamping conditions that can achieve consistent failure in the midregion of small arterial specimens, even for vessels from older individuals. Failure location was assessed in 17 dogbone specimens from human cerebral and sheep carotid arteries using soft inserts. For comparison with commonly used protocols, an additional 22 rectangular samples were tested using either sandpaper or foam tape inserts. Midsample failure was achieved in 94% of the dogbone specimens, while only 14% of the rectangular samples failed in the midregion, the other 86% failing close to the clamps. Additionally, we found midregion failure was more likely to be abrupt, caused by cracking or necking. In contrast, clamp failure was more likely to be gradual and included a delamination mode not seen in midregion failure. Hence, this work provides an approach that can be used to obtain consistent midspecimen failure, avoiding confounding clamp-related artifacts. Furthermore, with consistent midregion failure, studies can be designed to image the failure process in small vascular samples providing valuable quantitative information about changes to collagen and elastin structure during the failure process.

Download Full-text

Failure Properties and Stability Monitoring of Strip and Column Cemented Gangue Backfill Bodies Under Uniaxial Compression In Constructional Backfill Mining

10.21203/rs.3.rs-1120748/v1 ◽

2022 ◽

Author(s):

Hongyu Ran ◽

Yuxia Guo ◽

Guorui Feng ◽

Chunqing Li

Keyword(s):

Mechanical Properties ◽

Uniaxial Compression ◽

Constitutive Models ◽

Peak Stress ◽

Peak Strain ◽

Height Ratio ◽

Stability Monitoring ◽

Backfill Mining ◽

Failure Properties ◽

The Stability

Abstract The strip and column cemented gangue backfill bodies (CGBBs) are the main supporting components in the design of constructional backfill mining for coal mining, which determines the stability of goaf. Previous researches have mostly focused on the mechanical properties of column CGBB, but the mechanical properties of strip CGBB are still unclear. Herein, the uniaxial compression experiments for strip and column CGBBs were conducted to compare the failure properties. The acoustic emission (AE) and two types of resistivity monitoring were used to monitor the damage evolution. The effect of the length-height ratio on the mechanical characteristic of strip CGBB was analyzed by discrete element simulation. The results show that: the strength and peak strain of strip CGBB under uniaxial compression is higher than those of column CGBB, and the strip CGBB shows better ductility. The stress of column CGBB decreases significantly faster than that of strip CGBB at the post-peak stage. The strength and ductility of strip CGBB increase with the increase of length-height ratio. The strip CGBB is destroyed from both ends to the middle under uniaxial compression, and the core bearing area is reduced correspondingly. The AE signal evolution of CGBBs under uniaxial compression before the peak stress contains three stages, and the AE signals of strip CGBB at the peak stress will not rise sharply compared with column CGBB. The resistivity monitoring effect of the horizontally symmetrical conductive mesh is better than that of the axial. The horizontal resistivity increases gradually with the increase of stress under uniaxial compression, and increases sharply at the peak stress, and then drops after the peak stress. The damage constitutive models and the stability monitoring models of the CGBBs are established based on the experimental results. This work would be instructive for the design and stability monitoring of CGBB.

Download Full-text

Endotoxin Alteration of the Mucopolysaccharide Blood Vessel Coating in Rats

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100050755 ◽

1974 ◽

Vol 32 ◽

pp. 148-149

Author(s):

D. E. Philpott ◽

A. Takahashi

Keyword(s):

Skeletal Muscle ◽

Endothelial Cells ◽

Salivary Gland ◽

Carotid Artery ◽

Basement Membrane ◽

Coronary Vessels ◽

Ruthenium Red ◽

E Coli ◽

Old Rats ◽

The Brain

Two month, eight month and two year old rats were treated with 10 or 20 mg/kg of E. Coli endotoxin I. P. The eight month old rats proved most resistant to the endotoxin. During fixation the aorta, carotid artery, basil arartery of the brain, coronary vessels of the heart, inner surfaces of the heart chambers, heart and skeletal muscle, lung, liver, kidney, spleen, brain, retina, trachae, intestine, salivary gland, adrenal gland and gingiva were treated with ruthenium red or alcian blue to preserve the mucopolysaccharide (MPS) coating. Five, 8 and 24 hrs of endotoxin treatment produced increasingly marked capillary damage, disappearance of the MPS coating, edema, destruction of endothelial cells and damage to the basement membrane in the liver, kidney and lung.

Download Full-text