scholarly journals One Year Evaluation of Material Properties Changes of Polylactide Parts in Various Hydrolytic Degradation Conditions

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1496 ◽  
Author(s):  
Angela Andrzejewska
Keyword(s):  
Mechanical Behavior ◽  
Ph Value ◽  
Statistical Significance ◽  
Optimal Choice ◽  
Percentage Change ◽  
Uniaxial Tensile ◽  
Biodegradable Materials ◽  
Uniaxial Tensile Test ◽  
Degradation Medium ◽  
One Year

Biodegradable biocompatible materials are widely used in medical applications. Determining the possibility of using biodegradable materials depends on determining the changes in their parameters over time due to degradation. The current scientific research on biodegradable materials has presented results based on research methods characterized by the different geometry and cross-section size of the specimen, type of degradation medium, or different pH value of the medium or maximum degradation time. This paper presents the results of a one-year study on the influence of the type of degradation medium on the changes in mechanical behavior and the uptake of the degradation medium by biodegradable specimens with large cross-sections. In addition, a prototype of a test stand was created, which allowed for the specimens to be stored vertically to ensure regular medium exposure and eliminate the interaction of the surface of the tested specimens with the sides of the container. The obtained results allowed the statistical significance of differences in the mechanical parameters determined in the uniaxial tensile test after 2, 4, 6, 12, 26, 39, and 52 weeks of degradation to be indicated depending on the type of degradation medium. It was proven that the changes in mechanical behavior depend on the percentage change in the mass of the specimens during degradation. The percentage change in mass depends on the type of degradation medium. Based on the results of this research, it was noted that in long-term degradation above 12 weeks, buffered sodium chloride solution is the optimal choice for the degradation medium. However, distilled water or physiological saline solution can be used as an alternative during the degradation period for up to 12 weeks.

scholarly journals Experimental and Numerical Evaluation of Mechanical Properties of 3D-Printed Stainless Steel 316L Lattice Structures

2021 ◽  
Author(s):  
M. Carraturo ◽  
G. Alaimo ◽  
S. Marconi ◽  
E. Negrello ◽  
E. Sgambitterra ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Mechanical Behavior ◽  
Numerical Simulations ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Lattice Structures ◽  
Stainless Steel 316L ◽  
Research Attention ◽  
Octet Truss

AbstractAdditive manufacturing (AM), and in particular selective laser melting (SLM) technology, allows to produce structural components made of lattice structures. These kinds of structures have received a lot of research attention over recent years due to their capacity to generate easy-to-manufacture and lightweight components with enhanced mechanical properties. Despite a large amount of work available in the literature, the prediction of the mechanical behavior of lattice structures is still an open issue for researchers. Numerical simulations can help to better understand the mechanical behavior of such a kind of structure without undergoing long and expensive experimental campaigns. In this work, we compare numerical and experimental results of a uniaxial tensile test for stainless steel 316L octet-truss lattice specimen. Numerical simulations are based on both the nominal as-designed geometry and the as-build geometry obtained through the analysis of µ-CT images. We find that the use of the as-build geometry is fundamental for an accurate prediction of the mechanical behavior of lattice structures.

scholarly journals Effect of Decellularization Protocol on the Mechanical Behavior of Porcine Descending Aorta

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
John C. Fitzpatrick ◽  
Peter M. Clark ◽  
Franco M. Capaldi
Keyword(s):  
Mechanical Behavior ◽  
Vascular Tissue ◽  
Statistical Significance ◽  
Sodium Deoxycholate ◽  
Rnase A ◽  
Uniaxial Tensile ◽  
Aortic Tissue ◽  
Model Parameters ◽  
Test Analysis ◽  
Tissue Samples

Enzymatic-detergent decellularization treatments may use a combination of chemical reagents to reduce vascular tissue to sterilized scaffolds, which may be seeded with endothelial cells and implanted with a low risk of rejection. However, these chemicals may alter the mechanical properties of the native tissue and contribute to graft compliance mismatch. Uniaxial tensile data obtained from native and decellularized longitudinal aortic tissue samples was analyzed in terms of engineering stress and fit to a modified form of the Yeoh rubber model. One decellularization protocol used SDS, while the other two used TritonX-100, RNase-A, and DNase-I in combination with EDTA or sodium-deoxycholate. Statistical significance of Yeoh model parameters was determined by pairedt-test analysis. The TritonX-100/EDTA and 0.075% SDS treatments resulted in relatively variable mechanical changes and did not effectively lyse VSMCs in aortic tissue. The TritonX-100/sodium-deoxycholate treatment effectively lysed VSMCs and was characterized by less variability in mechanical behavior. The data suggests a TritonX-100/sodium-deoxycholate treatment is a more effective option than TritonX-100/EDTA and SDS treatments for the preparation of aortic xenografts and allografts because it effectively lyses VSMCs and is the least likely treatment, among those considered, to promote a decrease in mechanical compliance.

LONG-TERM MECHANICAL BEHAVIOR OF A GREEN CEMENTITIOUS COMPOSITE

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
H. Tian ◽  
Y. X. Zhang
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Mechanical Behavior ◽  
Building Materials ◽  
Weather Condition ◽  
Mechanical Tests ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Commercial Building

In this paper, a new green hybrid bagasse fiber (3% by volume) and steel fiber (0.7% by volume) reinforced cementitious composites with high volume fly ash (fly ash to cement ratio of 1.6) is developed and cured in weather condition up to 10 months. Basic mechanical tests, such as compressive test, Young’s modulus test, flexural test, and uniaxial tensile test and SEM tests were conducted at the age of 28 days, 3 months, 6 months and 10 months, respectively. Through comparison with the mechanical behavior of the composite at the age of 28 days, the long-term effect on the mechanical properties of the composite is evaluated. It is found the mechanical properties of the new composite increases greatly with aging. At the age of 10 months, the composite becomes more compacted and the composite is of excellent mechanical properties making it very promising to be used as commercial building materials.

scholarly journals Determination of the Material Parameters in the Holzapfel-Gasser-Ogden Constitutive Model for Simulation of Age-Dependent Material Nonlinear Behavior for Aortic Wall Tissue under Uniaxial Tension

2019 ◽  
Vol 9 (14) ◽  
pp. 2851 ◽  
Author(s):  
Up Huh ◽  
Chung-Won Lee ◽  
Ji-Hun You ◽  
Chan-Hee Song ◽  
Chi-Seung Lee ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Nonlinear Behavior ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Computational Simulations ◽  
Healthy Human ◽  
Element Analysis ◽  
Material Parameters ◽  
Hgo Model

In this study, computational simulations and experiments were performed to investigate the mechanical behavior of the aorta wall because of the increasing occurrences of aorta-related diseases. The study focused on the deformation and strength of porcine and healthy human abdominal aortic tissues under uniaxial tensile loading. The experiments for the mechanical behavior of the arterial tissue were conducted using a uniaxial tensile test apparatus to validate the simulation results. In addition, the strength and stretching of the tissues in the abdominal aorta of a healthy human as a function of age were investigated based on the uniaxial tensile tests. Moreover, computational simulations using the ABAQUS finite element analysis program were conducted on the experimental scenarios based on age, and the Holzapfel–Gasser–Ogden (HGO) model was applied during the simulation. The material parameters and formulae to be used in the HGO model were proposed to identify the failure stress and stretch correlation with age.

Effect of Orientation on Mechanical Behavior of an Extruded Al Alloy

2008 ◽  
Author(s):  
M. A. Malik ◽  
I. Salam ◽  
W. Muhammad
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Transverse Orientation ◽  
Longitudinal Orientation

The extruded materials are extensively used in chemical, food and nuclear industry and generally offer a unique combination of strength and freedom with regard to design solutions. During extrusion, material flow occurs in the direction of applied force and as a result microstructure change. The process ultimately induces variation in the mechanical properties when tested along or across the extrusion direction. The uniaxial tensile test is a simple and versatile test to expose most of the mechanical properties of the materials required to ensure the reliability of the systems. In present study, the mechanical behavior of an Al-Mg-Si alloy extruded cylinder has been determined with the help of uniaxial tensile test in longitudinal and transverse orientations. The microstructural features revealed significant difference in two orientations and constituent particles were found aligned in the direction of extrusion. Tensile tests were conducted in displacement mode at different cross head speeds corresponding to strain rates ranging from 10−5 to 10−1 s−1. The tests were conducted at ambient temperature in air atmosphere. The data thus obtained include: yield strength, ultimate tensile strength, percent elongation and reduction of area. Comparing the trends of strength variation, the material shows higher yield strength in longitudinal orientation as compared to transverse orientation. A slight increase in the yield strength with increasing strain rate was found in both the orientations. The ultimate tensile strength in both the directions was found similar and there was no appreciable change with increasing strain rate. The elongation and reduction in area were found higher in the longitudinal orientation. The effect of strain rate on these properties was negligible up to maximum speed tested. In longitudinal orientation typical dimpled fracture was observed indicating deformation before failure. In transverse orientation shallow dimples were present. The present study revealed that the distribution of constituent particles in an extruded thick-walled cylinder has a pronounced effect on its mechanical behavior and fracture morphology.

scholarly journals Numerical Modeling and Experimental Verification for High-Speed Forming of Al5052 with Single Current Pulse

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1311
Author(s):  
Hyeong-Gyu Park ◽  
Beom-Soo Kang ◽  
Jeong Kim
Keyword(s):  
Mechanical Behavior ◽  
Thermal Effect ◽  
Electric Current ◽  
Current Pulse ◽  
High Speed ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Electric Current Pulse ◽  
Current Pulses ◽  
Electric Current Pulses

Application of electric current pulses during plastic deformation changes the mechanical behavior owing to the electro-plastic effect. The effect of electric current pulses on the Al5052 alloy is investigated in this study. In order to demonstrate the advantages of passing electric current pulses through a metal sheet during the forming process, a uniaxial tensile test with an electric current pulse was carried out using a self-designed device; this device can apply a 2-kA electric current pulse to the specimen for a short period (>100ms). The electric current increases the temperature of the specimen due to Joule heating. It is, therefore, necessary to decouple the thermal effect from the overall behavior to understand only the contribution of electric current in the mechanical behavior. Firstly, an electro-thermo-mechanical finite element study of an electrically assisted uniaxial tensile test of Al5052 alloy is performed to isolate the thermal effect. The simulated results yielded the thermal effect due to the electric current. By comparing the experimental and simulated results, the contribution of electric current is decoupled from that of thermal effect. The electric current-dependent material model is implemented into the commercial FEM code LS-DYNA using user-defined material(UMAT) subroutine. The electric current-dependent material model was used to simulate the electro-mechanical finite element analysis of the high-speed forming of an aluminum sheet with electric current pulse. Simulation results were compared with experimental results at several applied electric currents to evaluate the accuracy of the UMAT. The present work can be utilized to develop simpler constitutive models for the mechanical behavior of metals subjected to a pulsed electric current.

Influence of post-welding tempering on mechanical behavior of friction welded joints from medium-carbon steels during tensile test

2020 ◽  
pp. 40-49
Author(s):  
A. S. Atamashkin ◽  
E. Yu. Priymak ◽  
N. V. Firsova
Keyword(s):  
Mechanical Behavior ◽  
Welded Joints ◽  
Welded Joint ◽  
Crack Nucleation ◽  
Carbon Steels ◽  
Uniaxial Tensile ◽  
Medium Carbon ◽  
Uniaxial Tensile Testing ◽  
Rotary Friction Welding ◽  
Medium Carbon Steels

The paper presents an analysis of the mechanical behavior of friction samples of welded joints from steels 30G2 (36 Mn 5) and 40 KhN (40Ni Cr 6), made by rotary friction welding (RFW). The influence of various temperature conditions of postweld tempering on the mechanical properties and deformation behavior during uniaxial tensile testing is analyzed. Vulnerabilities where crack nucleation and propagation occurred in specimens with a welded joint were identified. It was found that with this combination of steels, postweld tempering of the welded joint contributes to a decrease in the integral strength characteristics under conditions of static tension along with a significant decrease in the relative longitudinal deformation of the tested samples.

scholarly journals Biomechanical-Structural Correlation of Chordae tendineae in Animal Models: A Pilot Study

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1678
Author(s):  
Justyn Gach ◽  
Izabela Janus ◽  
Agnieszka Mackiewicz ◽  
Tomasz Klekiel ◽  
Agnieszka Noszczyk-Nowak
Keyword(s):  
Mitral Valve ◽  
Complex Structure ◽  
Future Research ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Histopathological Analysis ◽  
Papillary Muscles ◽  
Chordae Tendineae ◽  
Structural Correlation ◽  
Ring Valve

The mitral valve apparatus is a complex structure consisting of the mitral ring, valve leaflets, papillary muscles and chordae tendineae (CT). The latter are mainly responsible for the mechanical functions of the valve. Our study included investigations of the biomechanical and structural properties of CT collected from canine and porcine hearts, as there are no studies about these properties of canine CT. We performed a static uniaxial tensile test on CT samples and a histopathological analysis in order to examine their microstructure. The results were analyzed to clarify whether the changes in mechanical persistence of chordae tendineae are combined with the alterations in their structure. This study offers clinical insight for future research, allowing for an understanding of the process of chordae tendineae rupture that happens during degenerative mitral valve disease—the most common heart disease in dogs.

scholarly journals Polar poly(n-butyl acrylate)-g-polyacrylonitrile elastomer with high temperature elasticity and healability as flexible electronic substrate

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Yuzhu Zheng ◽  
Deli Xu ◽  
Shiyou Tian ◽  
Manli Li ◽  
Wenwen Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Graft Copolymer ◽  
Butyl Acrylate ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Self Healing ◽  
Chemical Structures ◽  
Flexible Electronic ◽  
Ag Nanowires ◽  
Cyano Groups

AbstractIn this work, graft copolymer poly (n-butyl acrylate)-g-polyacrylonitrile with poly (n-butyl acrylate) as backbones and polyacrylonitrile as side chains (PnBA-g-PAN) was synthesized by macromonomer method and emulsion polymerization. The macromonomer was synthesized by atom transfer radical polymerization and end-group modification. The chemical structures and thermal properties of macromonomer and graft copolymer were investigated by FTIR, GPC, NMR and TGA, etc. The mechanical properties of graft copolymer elastomer was also measured by uniaxial tensile test. Rheological properties at different temperature and mechanical property demonstrated that graft copolymer elastomer possessed elasticity until 180 oC because of cyclization of cyano groups. Ag nanowires@PnBA-g-PAN composite elastomer was developed, and the resulted material exhibited autonomic healing property on account of segments’ flexibility and dynamic interaction between Ag nanowires (AgNWs) and cyano groups. This is a general method for generation of elastomer with high temperature elasticity and fast self-healing. The composite elastomer has potential application in flexible electronic conductor.

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