scholarly journals Mechanical Characterization of Nanocomposite Joints Based on Biomedical Grade Polyethylene under Cyclical Loads

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2681
Author(s):  
Annamaria Visco ◽  
Cristina Scolaro ◽  
Antonino Quattrocchi ◽  
Roberto Montanini
Keyword(s):  
Titanium Dioxide ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Laser Light ◽  
Mechanical Tests ◽  
Fatigue Tests ◽  
Weight Content ◽  
Percentage Weight ◽  
Static Mechanical

Polymeric joints, made of biomedical polyethylene (UHMWPE) nanocomposite sheets, were welded with a diode laser. Since polyethylene does not absorb laser light, nanocomposites were prepared containing different percentages by weight of titanium dioxide as it is a laser absorbent. The joints were first analyzed with static mechanical tests to establish the best percentage weight content of filler that had the best mechanical response. Then, the nanocomposites containing 1 wt% titanium dioxide were selected (white color) to be subjected to fatigue tests. The experimental results were also compared with those obtained on UMMWPE with a different laser light absorbent nano filler (carbon, with greater laser absorbing power, gray in color), already studied by our research team. The results showed that the two types of joints had an appreciable resistance to fatigue, depending on the various loads imposed. Therefore, they can be chosen in different applications of UHMWPE, depending on the stresses imposed during their use.

scholarly journals Visco-Hyperelastic Characterization of the Equine Immature Zona Pellucida

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1223
Author(s):  
Elisa Ficarella ◽  
Mohammad Minooei ◽  
Lorenzo Santoro ◽  
Elisabetta Toma ◽  
Bartolomeo Trentadue ◽  
...  
Keyword(s):  
Zona Pellucida ◽  
Soft Matter ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Nonlinear Material ◽  
Prony Series ◽  
Critical Comparison ◽  
Highly Nonlinear ◽  
Good Agreement

This article presents a very detailed study on the mechanical characterization of a highly nonlinear material, the immature equine zona pellucida (ZP) membrane. The ZP is modeled as a visco-hyperelastic soft matter. The Arruda–Boyce constitutive equation and the two-term Prony series are identified as the most suitable models for describing the hyperelastic and viscous components, respectively, of the ZP’s mechanical response. Material properties are identified via inverse analysis based on nonlinear optimization which fits nanoindentation curves recorded at different rates. The suitability of the proposed approach is fully demonstrated by the very good agreement between AFM data and numerically reconstructed force–indentation curves. A critical comparison of mechanical behavior of two immature ZP membranes (i.e., equine and porcine ZPs) is also carried out considering the information on the structure of these materials available from electron microscopy investigations documented in the literature.

scholarly journals Role of smooth muscle activation in the static and dynamic mechanical characterization of human aortas

2022 ◽  
Vol 119 (3) ◽  
pp. e2117232119
Author(s):  
Giulio Franchini ◽  
Ivan D. Breslavsky ◽  
Francesco Giovanniello ◽  
Ali Kassab ◽  
Gerhard A. Holzapfel ◽  
...  
Keyword(s):  
Experimental Data ◽  
Smooth Muscle ◽  
Muscle Activation ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Viscoelastic Behavior ◽  
Material Model ◽  
Suitable Material ◽  
Dynamic Mechanical

Experimental data and a suitable material model for human aortas with smooth muscle activation are not available in the literature despite the need for developing advanced grafts; the present study closes this gap. Mechanical characterization of human descending thoracic aortas was performed with and without vascular smooth muscle (VSM) activation. Specimens were taken from 13 heart-beating donors. The aortic segments were cooled in Belzer UW solution during transport and tested within a few hours after explantation. VSM activation was achieved through the use of potassium depolarization and noradrenaline as vasoactive agents. In addition to isometric activation experiments, the quasistatic passive and active stress–strain curves were obtained for circumferential and longitudinal strips of the aortic material. This characterization made it possible to create an original mechanical model of the active aortic material that accurately fits the experimental data. The dynamic mechanical characterization was executed using cyclic strain at different frequencies of physiological interest. An initial prestretch, which corresponded to the physiological conditions, was applied before cyclic loading. Dynamic tests made it possible to identify the differences in the viscoelastic behavior of the passive and active tissue. This work illustrates the importance of VSM activation for the static and dynamic mechanical response of human aortas. Most importantly, this study provides material data and a material model for the development of a future generation of active aortic grafts that mimic natural behavior and help regulate blood pressure.

Mechanical Characterization of the Decellularized Porcine Small Intestinal Submucosa Extracellular Matrix

2013 ◽  
Author(s):  
Shijia Zhao ◽  
Linxia Gu ◽  
James M. Hammel ◽  
Haili Lang
Keyword(s):  
Mechanical Properties ◽  
Extracellular Matrix ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Small Intestinal Submucosa ◽  
Trade Name ◽  
Porcine Small Intestinal Submucosa ◽  
Small Intestinal ◽  
Intestinal Submucosa

In this work, the decellularized porcine small intestinal submucosa extracellular matrix (SIS-ECM), obtained from the commercial product under the trade name of CorMatrix, were tested in uniaxial tension. Preconditioning under cyclic loading of 2 N was conducted to stabilize the mechanical response of the tissue. The influence of rehydration time on the mechanical properties of the tissue was evaluated. Results suggested that the stiffness of SIS-ECM decreased with longer rehydration time. Considering the application of CorMatrix in pericardial closure, the native pericardium samples were also tested. The comparison indicated that the native pericardium is softer than rehydrated CorMatrix. This work can facilitate the surgeons to better choose the appropriate rehydration time when conducting the extracardiac implantations, such as pericardial reconstruction, pericardial closure, etc.

scholarly journals Position-dependent mechanical characterization of the PBF-EB-manufactured Ti6Al4V alloy

2021 ◽  
Author(s):  
Daniel Kotzem ◽  
Alexandra Höffgen ◽  
Rajevan Raveendran ◽  
Felix Stern ◽  
Kerstin Möhring ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Material Properties ◽  
Mechanical Characterization ◽  
Industrial Applications ◽  
Fatigue Tests ◽  
Ti6al4v Alloy ◽  
Effective Diameter ◽  
Powder Bed Fusion ◽  
Powder Bed

AbstractBy means of additive manufacturing, the production of components with nearly unlimited geometrical design complexity is feasible. Especially, powder bed fusion techniques such as electron beam powder bed fusion (PBF-EB) are currently focused. However, equal material properties are mandatory to be able to transfer this technique to a wide scope of industrial applications. Within the scope of this work, the mechanical properties of the PBF-EB-manufactured Ti6Al4V alloy are investigated as a function of the position on the building platform. It can be stated that as-built surface roughness changes within building platform whereby highest surface roughness detected by computed tomography (Ra = 46.0 ± 5.3 µm) was found for specimens located in the front of the building platform. In contrast, no significant differences in relative density could be determined and specimens can be assumed as nearly fully dense (> 99.9%). Furthermore, all specimens are affected by an undersized effective diameter compared to the CAD data. Fatigue tests revealed that specimens in the front of the building platform show slightly lower performance at higher stress amplitudes as compared to specimens in the back of the building platform. However, process-induced notch-like defects based on the surface roughness were found to be the preferred location for early crack initiation.

scholarly journals Preparation, morphological, and mechanical characterization of titanium dioxide (TiO2)/polyvinyl alcohol (PVA) composite for gamma-rays radiation shielding

2019 ◽  
Vol 1279 ◽  
pp. 012019 ◽  
Author(s):  
R. K. Fakher Alfahed ◽  
Kareem K. Mohammad ◽  
Munaf S. Majeed ◽  
Hussain Ali Badran ◽  
Kamal M. Ali ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Polyvinyl Alcohol ◽  
Gamma Rays ◽  
Mechanical Characterization ◽  
Radiation Shielding

Functional Characterization of NiTi Shape Memory Elements for Smart Micro-Actuation

2013 ◽  
Author(s):  
Carlo Alberto Biffi ◽  
Luca Bonacina ◽  
Adelaide Nespoli ◽  
Barbara Previtali ◽  
Ausonio Tuissi
Keyword(s):  
Shape Memory ◽  
Mechanical Response ◽  
Thermal Hysteresis ◽  
Functional Characterization ◽  
Functional Materials ◽  
Mechanical Tests ◽  
Calorimetric Analysis ◽  
Production Route ◽  
Definition Of

Shape Memory Alloys (SMAs) are smart and functional materials, which are considered good candidates for the activation of devices for the automotive, aerospace, biomedical and mechanical systems, thanks to the shape memory effect. In this work, a study on the mechanical response of NiTi SMA snake like elements has been proposed. The production route of these elements from thin sheets, was given by laser machining followed by chemical etching. The micro-elements were characterized by means of calorimetric analysis for the definition of the theoretical operating temperatures and by means of thermo-mechanical testing for the evaluation of their functional performances. Mechanical tests has been carried out to assess the tensile behavior of martensite and austenite separately, and to evaluate the thermal hysteresis under different constant loads. Moreover, Finite Element Modeling (FEM) has been also accomplished to study the numerical evaluation of the stress field that origins by the application of the different loads in both the martensitic and austenitic phases.

Influence of the Embedding Media on the Results of Standard In Vitro Fatigue Tests on the Femoral Components

1994 ◽  
Vol 208 (3) ◽  
pp. 131-137 ◽  
Author(s):  
M Viceconti ◽  
A Toni ◽  
A Giunti
Keyword(s):  
Mechanical Properties ◽  
Stress Analysis ◽  
Mechanical Tests ◽  
Fatigue Tests ◽  
Strain Gauges ◽  
Static Properties ◽  
Static Mechanical ◽  
Hip Stems ◽  
Dental Applications

The aim of the present investigation was to determine the effects of the embedding material mechanical properties on the in vitro fatigue endurance of femoral hip stems as determined following ISO standards. Acrylic cements are usually employed as embedding media; due to the high cost of surgical cements, acrylic cements for dental applications are commonly used. Two acrylic cements for dental applications were tested to determine their static mechanical properties and compared with those found for three surgical cements. The same two dental cements were also compared as embedding media in a series of ISO 7206/3 fatigue tests on a mini-size Cr-Co stem; prosthesis stress analysis using strain gauges was also performed. The mechanical tests on the different cements showed that behind the definition of acrylic cement are materials with considerably different mechanical static properties. The fatigue campaign confirmed the influence of embedding media on the results obtained from the ISO 7206/3 fatigue test. Under a load of 4200 N the stem failed after four million cycles when using one cement; it did not fail after ten million cycles when using another cement. Stress analysis with strain gauges substantially confirmed these findings.

scholarly journals Biomechanical Comparison of Glutaraldehyde-Crosslinked Gelatin Fibrinogen Electrospun Scaffolds to Porcine Coronary Arteries

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
E. Tamimi ◽  
D. C. Ardila ◽  
D. G. Haskett ◽  
T. Doetschman ◽  
M. J. Slepian ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Mechanical Characterization ◽  
Artery Bypass ◽  
Bypass Graft ◽  
Vein Grafts ◽  
Electrospun Scaffolds ◽  
Response Data ◽  
Custom Made ◽  
Biomechanical Comparison

Cardiovascular disease (CVD) is the leading cause of death for Americans. As coronary artery bypass graft surgery (CABG) remains a mainstay of therapy for CVD and native vein grafts are limited by issues of supply and lifespan, an effective readily available tissue-engineered vascular graft (TEVG) for use in CABG would provide drastic improvements in patient care. Biomechanical mismatch between vascular grafts and native vasculature has been shown to be the major cause of graft failure, and therefore, there is need for compliance-matched biocompatible TEVGs for clinical implantation. The current study investigates the biaxial mechanical characterization of acellular electrospun glutaraldehyde (GLUT) vapor-crosslinked gelatin/fibrinogen cylindrical constructs, using a custom-made microbiaxial optomechanical device (MOD). Constructs crosslinked for 2, 8, and 24 hrs are compared to mechanically characterized porcine left anterior descending coronary (LADC) artery. The mechanical response data were used for constitutive modeling using a modified Fung strain energy equation. The results showed that constructs crosslinked for 2 and 8 hrs exhibited circumferential and axial tangential moduli (ATM) similar to that of the LADC. Furthermore, the 8-hrs experimental group was the only one to compliance-match the LADC, with compliance values of 0.0006±0.00018 mm Hg−1 and 0.00071±0.00027 mm Hg−1, respectively. The results of this study show the feasibility of meeting mechanical specifications expected of native arteries through manipulating GLUT vapor crosslinking time. The comprehensive mechanical characterization of cylindrical biopolymer constructs in this study is an important first step to successfully develop a biopolymer compliance-matched TEVG.

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