A Two Dimensional Phenomenological Model for Damage of Arteries

2007 ◽  
Author(s):  
Alexander Rachev
Keyword(s):  
Mechanical Strength ◽  
Vascular Tissue ◽  
Longitudinal Direction ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Traumatic Rupture ◽  
Artery Graft ◽  
Arterial Tissue ◽  
Static Tensile ◽  
Failure Properties

Loss of mechanical strength of arteries can manifest itself in many ways including rupture of a vulnerable atherosclerotic plaques, burst of saccular aneurisms, rupture of artery/graft anastomosis, and traumatic rupture of aorta by impact loading due to automobile accidents. In all cases the fracture of the tissue leads to sudden cardiovascular events that often have a lethal end. To date there are insufficient experimental data on the mechanical strength of healthy and diseased vascular tissue. Most of the results refer to the failure properties from uniaxial quasi-static tensile tests on strips and rings. It was found that the tensile strength is different in the circumferential and longitudinal direction especially when it is determined from strain controlled dynamic tests [1]. Results form load-controlled fatigue tests have shown a gradual softening of the arterial tissue, development of a residual (plastic) deformation, and existence of S-N curve [2]. However, the information from uniaxial tests is not sufficient to predict the damage of tubular segments due to coupling between circumferential and longitudinal stress via constitutive equations and deformed geometry. Moreover, the mechanisms of arterial tissue failure remain unknown.

scholarly journals Investigations on arc brazing for galvanized heavy steel plates in steel and shipbuilding

2021 ◽  
Author(s):  
Philipp Andreazza ◽  
Andreas Gericke ◽  
Knuth-Michael Henkel
Keyword(s):  
Low Cost ◽  
Thin Sheet ◽  
Steel Structures ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Steel Plates ◽  
Galvanized Steel ◽  
Filler Materials ◽  
Static Tensile ◽  
Brazed Joints

AbstractArc brazing with low-melting copper-based filler materials, which has long been established and standardized in the thin sheet sector, offers numerous advantages in the processing of predominantly electrolytically galvanized steel structures. In steel and shipbuilding, on the other hand, equipment parts made of thick steel sheets are hot-dip galvanized at low cost and with good corrosion-inhibiting properties. Quality welding of such constructions is not possible without special precautions such as removing the zinc layer and subsequent recoating. With regard to greater plate thicknesses, arc brazing was analyzed in these investigations as an alternative joining method with regard to its suitability for practical use. Within the scope of the investigations, CuSi3Mn, CuMn12Ni2, and four different aluminum bronzes were examined on different sheet surface conditions with regard to the geometrical and production parameters. This was carried out by build-up and connection brazing, executed as butt and cross joints. Quasi-static tensile tests and fatigue tests were used to assess the strength behavior. In addition, metallographic analyses are carried out as well as hardness tests. The suitability for multi-layer brazing and the tendency to distortion were also investigated, as well as the behavior of arc brazed joints under corrosive conditions.

Mechanical Properties of Flat Braided Composites With a Circular Hole

1999 ◽  
Author(s):  
Takeru Ohki ◽  
Shinya Ikegaki ◽  
Ken Kurasiki ◽  
Hiroyuki Hamada ◽  
Masaharu Iwamoto
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Circular Hole ◽  
Fracture Behavior ◽  
Fatigue Property ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Braided Composites ◽  
Static Tensile ◽  
The One

Abstract In this study, fracture behavior and strength in the flat braided bar with a circular hole were investigated by static and fatigue test. Two type of specimens were prepared. They are a braided flat bar with an integrally-formed braided hole and a braided flat bar with a machined hole. Moreover, we also examined a specimen that had a metal pin inserted at the circular hole. This specimen was subjected to a static tensile test. The results of the tensile tests indicate that the strength of the flat bar with a braided hole was larger than that of the one with the machined hole. Furthermore, from the results of the fatigue tests, the flat bar with the braided hole showed higher fatigue property than that of the one with the machined hole.

Mechanical Properties of Flat Braided Composites With a Circular Hole

2000 ◽  
Vol 122 (4) ◽  
pp. 420-424 ◽  
Author(s):  
Takeru Ohki ◽  
Shinya Ikegaki ◽  
Ken Kurasiki ◽  
Hiroyuki Hamada ◽  
Masaharu Iwamoto
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Circular Hole ◽  
Fracture Behavior ◽  
Fatigue Property ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Braided Composites ◽  
Static Tensile ◽  
The One

In this study, fracture behavior and strength in the flat braided bar with a circular hole were investigated by static and fatigue test. Two types of specimen were prepared. They are a braided flat bar with an integrally formed braided hole and a braided flat bar with a machined hole. Moreover, we also examined a specimen that had a metal pin inserted at the circular hole. This specimen was subjected to a static tensile test. The results of the tensile tests indicate that the strength of the flat bar with a braided hole was larger than that of the one with the machined hole. Furthermore, from the results of the fatigue tests, the flat bar with the braided hole showed higher fatigue property than that of the one with the machined hole. [S0094-4289(00)02604-9]

Effect of transverse reinforcement on cracking of CFRP composite laminates under static and fatigue loads

2020 ◽  
Vol 54 (25) ◽  
pp. 3755-3766 ◽  
Author(s):  
Maciej Giżyński
Keyword(s):  
Composite Laminates ◽  
Crack Density ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Transverse Reinforcement ◽  
Damage Growth ◽  
Cfrp Laminates ◽  
Cfrp Composite ◽  
Static Tensile

Several CFRP laminates with various layups, possessing two distinctive forms of transverse reinforcement either UD 90° or fabric 0°/90°, were tested in both static and fatigue tests. All examined layups were considered to be used in the wingbox design of the multipurpose turboprop aircraft. In-situ microscopic observations were carried out during the tests. Static tensile tests allowed to find the strength of the laminas, stress, and strains at which cracks started to propagate, crack density during the test. The microscopic observations allowed to establish cracks’ growth paths. The first crack in laminates having fabric 0°/90° laminas usually was observed for higher stress and strain than in laminates with UD 90° laminas. Also, the later ones showed a tendency to significantly delaminate along the interface between UD 90° and UD 45° laminas. The fatigue test was carried out in order to find how to distinguish damage growth in both families of laminates that affects their fatigue life. As an outcome, S-N lines were determined. During the test the microscopic observations were made, which allowed to show crack and delamination growth during successive load cycles. The microscopic observations showed that cyclic loading leads to the fast growth of delaminations at the interface of fabric 0°/90°ply or UD 90° laminas.

Tensile and Fatigue Testings of Hybrid Al/APC-2 Nanocomposite Laminates at Elevated Temperature

2008 ◽  
Vol 47-50 ◽  
pp. 592-595 ◽  
Author(s):  
Ming Hwa R. Jen ◽  
Yi Chun Sung ◽  
Yin Da Lai
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Thermoplastic Matrix ◽  
Longitudinal Stiffness ◽  
Hybrid Laminates ◽  
Static Tensile ◽  
Aluminum Alloy 2024 ◽  
Strength And Stiffness

To deal with the stringent operational demands the aerospace structural materials of light weight Aluminum alloy 2024 sheets and plies of carbon fibers reinforced thermoplastic matrix PEEK were used to sustain at least 80% of their mechanical properties at elevated temperature. The addition of nanoparticles SiO2 can enhance the composite laminate strength and stiffness. Also, Al 2024 sheets were treated by an anodic method of electroplating to increase surface roughness to achieve perfectly bonding with matrix PEEK. Then, the modified diaphragm curing process was adopted to make the innovative hybrid Al/APC-2 hybrid nanocomposite laminates. Next, both static tensile and fatigue tests were conducted at elevated temperature to obtain the mechanical properties, lives and failure mechanisms to verify the improved features of hybrid specimens. From tensile tests the mechanical properties of Al/APC-2 [4Al/0/±45/90/2Al]s hybrid laminates at elevated temperature were obtained. Although there is a big drop at 150°C, the reduction in strength from RT to 125°C is generally not significant. The longitudinal stiffness is almost unchanged at elevated temperature. After cyclic tension-tension (T-T) tests, the positions of received S-N curves go downwards as temperature rising. No delaminations were found in both tests. If the applied stress normalized by the ultimate strength at corresponding temperature, the normalized S-N curves are closer with some curve positions reversed. Significant improvement of manufacturing and enhancement of mechanical properties in hybrid laminates were achieved finally.

scholarly journals Low- and High-Cycle Fatigue Behavior of FRCM Composites

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5412
Author(s):  
Angelo Savio Calabrese ◽  
Tommaso D’Antino ◽  
Pierluigi Colombi ◽  
Carlo Poggi
Keyword(s):  
Cyclic Loading ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Strain Curve ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Static Tensile

This paper describes methods, procedures, and results of cyclic loading tensile tests of a PBO FRCM composite. The main objective of the research is the evaluation of the effect of low- and high-cycle fatigue on the composite tensile properties, namely the tensile strength, ultimate tensile strain, and slope of the stress–strain curve. To this end, low- and high-cycle fatigue tests and post-fatigue tests were performed to study the composite behavior when subjected to cyclic loading and after being subjected to a different number of cycles. The results showed that the mean stress and amplitude of fatigue cycles affect the specimen behavior and mode of failure. In high-cycle fatigue tests, failure occurred due to progressive fiber filaments rupture. In low-cycle fatigue, the stress–strain response and failure mode were similar to those observed in quasi-static tensile tests. The results obtained provide important information on the fatigue behavior of PBO FRCM coupons, showing the need for further studies to better understand the behavior of existing concrete and masonry members strengthened with FRCM composites and subjected to cyclic loading.

Progressive damage characteristics of screwed single-lap CFRPI-metal joint subjected to tensile loading at RT and 350°C

2021 ◽  
pp. 002199832098559
Author(s):  
Yun-Tao Zhu ◽  
Jun-Jiang Xiong ◽  
Chu-Yang Luo ◽  
Yi-Sen Du
Keyword(s):  
Damage Model ◽  
Tensile Loading ◽  
Tensile Tests ◽  
Displacement Curve ◽  
Progressive Damage ◽  
Damage Characteristics ◽  
Metal Joint ◽  
Static Tensile ◽  
Strength And Stiffness ◽  
Progressive Damage Model

This paper outlines progressive damage characteristics of screwed single-lap CFRPI-metal joints subjected to tensile loading at RT (room temperature) and 350°C. Quasi-static tensile tests were performed on screwed single-lap CCF300/AC721-30CrMnSiA joint at RT and 350°C, and the load versus displacement curve, strength and stiffness of joint were gauged and discussed. With due consideration of thermal-mechanical interaction and complex failure mechanism, a modified progressive damage model (PDM) based on the mixed failure criterion was devised to simulate progressive damage characteristics of screwed single-lap CCF300/AC721-30CrMnSiA joint, and simulations correlate well with experiments. By using the PDM, the effects of geometry dimensions on mechanical characteristics of screwed single-lap CCF300/AC721-30CrMnSiA joint were analyzed and discussed.

scholarly journals Effective decellularisation of human saphenous veins for biocompatible arterial tissue engineering applications: Bench optimisation and feasibility in vivo testing

2021 ◽  
Vol 12 ◽  
pp. 204173142098752
Author(s):  
Nadiah S Sulaiman ◽  
Andrew R Bond ◽  
Vito D Bruno ◽  
John Joseph ◽  
Jason L Johnson ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Mechanical Strength ◽  
Vascular Tissue ◽  
Sodium Dodecyl ◽  
Host Cells ◽  
Replacement Model ◽  
In Vivo Testing ◽  
Vascular Scaffolds

Human saphenous vein (hSV) and synthetic grafts are commonly used conduits in vascular grafting, despite high failure rates. Decellularising hSVs (D-hSVs) to produce vascular scaffolds might be an effective alternative. We assessed the effectiveness of a detergent-based method using 0% to 1% sodium dodecyl sulphate (SDS) to decellularise hSV. Decellularisation effectiveness was measured in vitro by nuclear counting, DNA content, residual cell viability, extracellular matrix integrity and mechanical strength. Cytotoxicity was assessed on human and porcine cells. The most effective SDS concentration was used to prepare D-hSV grafts that underwent preliminary in vivo testing using a porcine carotid artery replacement model. Effective decellularisation was achieved with 0.01% SDS, and D-hSVs were biocompatible after seeding. In vivo xeno-transplantation confirmed excellent mechanical strength and biocompatibility with recruitment of host cells without mechanical failure, and a 50% patency rate at 4-weeks. We have developed a simple biocompatible methodology to effectively decellularise hSVs. This could enhance vascular tissue engineering toward future clinical applications.

scholarly journals The Performance of CR180IF and DP600 Laser Welded Steel Sheets under Different Strain Rates

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1553
Author(s):  
Mária Mihaliková ◽  
Kristína Zgodavová ◽  
Peter Bober ◽  
Anna Špegárová
Keyword(s):  
Sheet Steel ◽  
Testing Machine ◽  
Dynamic Test ◽  
Tensile Tests ◽  
Joint Surface ◽  
Strain Rates ◽  
Interstitial Free ◽  
Welded Steel ◽  
Steel Sheets ◽  
Static Tensile

The presented research background is a car body manufacturer’s request to test the car body’s components welded from dissimilar steel sheets. In view of the vehicle crew’s protection, it is necessary to study the static and dynamic behavior of welded steels. Therefore, the influence of laser welding on the mechanical and dynamical properties, microstructure, microhardness, and welded joint surface roughness of interstitial free CR180IF and dual-phase DP600 steels were investigated. Static tensile tests were carried out by using testing machine Zwick 1387, and dynamic test used rotary hammer machine RSO. Sheet steel was tested at different strain rates ranging from 10−3 to 103 s−1. The laser welds’ microstructure and microhardness were evaluated in the base metal, heat-affected zone, and fusion zone. The comprehensive analysis also included chemical analysis, fracture surface analysis, and roughness measurement. The research results showed that the strain rate had an influence on the mechanical properties of base materials and welded joints. The dynamic loading increases the yield stress more than the ultimate tensile strength for the monitored steels, while the most significant increase was recorded for the welded material.

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