EFFECT OF THERMAL DAMAGE ON COMPRESSIVE BEHAVIOR OF SKIN TISSUE

2009 ◽  
Vol 09 (01) ◽  
pp. 81-104 ◽  
Author(s):  
F. XU ◽  
T. J. LU ◽  
K. A. SEFFEN
Keyword(s):  
Mechanical Properties ◽  
Thermal Damage ◽  
Rate Sensitivity ◽  
Thermomechanical Behavior ◽  
Bioheat Transfer ◽  
Skin Tissue ◽  
Medical Applications ◽  
Compressive Behavior ◽  
Damage Degree

Biothermomechanics of skin tissue is highly interdisciplinary, involving bioheat transfer, burn damage, biomechanics and physiology. Characterization of the thermomechanical behavior of skin tissue is of great importance and can contribute to a variety of medical applications. However, few studies have attempted to address the influence of heat induced thermal damage on the mechanical properties of skin tissue. This paper presents the compressive behavior of pigskin at different thermal damage levels and discusses the possible mechanisms of thermal damage–dependent compressive behavior of skin. The results demonstrate that skin stiffness decreases with increasing thermal damage degree and there exists strain rate sensitivity at different damage levels, caused mainly by hydration changes.

Differences in petrophysical and mechanical properties between low- and middle-rank coal subjected to liquid nitrogen cooling in coalbed methane mining

2021 ◽  
pp. 1-10
Author(s):  
Menglin Du ◽  
Feng Gao ◽  
Chengzheng Cai ◽  
Shanjie Su ◽  
Zekai Wang
Keyword(s):  
Mechanical Properties ◽  
Pore Structure ◽  
Liquid Nitrogen ◽  
Coalbed Methane ◽  
Bituminous Coal ◽  
Thermal Damage ◽  
Physical And Mechanical Properties ◽  
Damage Degree ◽  
Lignite Coal ◽  
The Difference

Abstract Exploring the damage differences between different coal rank coal reservoirs subjected to liquid nitrogen (LN2) cooling is of great significance to the rational development and efficient utilization of coalbed methane. For this purpose, the mechanical properties, acoustic emission (AE) characteristics and energy evolution law of lignite and bituminous coal subjected to LN2 cooling were investigated based on the Brazilian splitting tests. Then, pore structure changes were analyzed to reveal the difference in the microscopic damage between lignite and bituminous coal after LN2 cooling. The results showed that compared with bituminous coal, the pore structure of lignite coal changed more obviously, which was manifested as follows: significant increases in porosity, pore diameters, and pore area; a larger transformation from micropores and transition pores to mesopores and macropores. After LN2 cooling, the thermal damage inside lignite and bituminous coal was 0.412 and 0.069, respectively. The thermal damage reduced the cohesive force between mineral particles, leading to the deterioration of the macroscopic physical and mechanical properties. Simultaneously, denser AE ringing counts and larger accumulated ringing counts were observed after LN2 cooling. Moreover, the random distribution of thermal damage enhanced the randomness of the macrocrack propagation direction, resulting in an increase in the crack path tortuosity. With more initial defects inside coal, a more obvious thermal damage degree and wider damage distribution will be induced by LN2 cooling, leading to more complicated crack formation paths and a higher fragmentation degree, such as that of lignite coal.

scholarly journals Revisión de Modelos Hiperelásticos utilizados en Tejidos

2018 ◽  
Vol 3 (1) ◽  
pp. 100
Author(s):  
Miguel Moreno ◽  
Carlos Plazaola ◽  
Guadalupe González ◽  
Mayteé Zambrano ◽  
Carmenza Spadafora
Keyword(s):  
Mechanical Properties ◽  
Soft Tissue ◽  
Literature Review ◽  
Soft Tissues ◽  
Mathematical Formulation ◽  
Medical Applications ◽  
Surgical Simulations ◽  
Mechanical Nature ◽  
Hyperelastic Models

This work is related to the hyperelastic models most used in soft tissue. The importance of obtaining accurate mechanical properties of tissues are of great interest for various medical applications, for example: in treatment of diseases and surgical simulations in real time. The aim of this literature review is to evaluate the models used for proposing a mathematical formulation and modelling the mechanical behaviour of a sequence of layers of soft tissues and your reply to undergo external actions of mechanical nature, in order to improve the techniques of characterization of soft tissues.Keywords: Biomechanical, Hyperelasticity, Mechanical Properties, Nonlinear elasticity, Soft Tissues.

Metallurgical Characterization of some Magnesium Alloys for Medical Applications

2012 ◽  
Vol 188 ◽  
pp. 109-113 ◽  
Author(s):  
Iulian Antoniac ◽  
Marian Miculescu ◽  
Mihaela Dinu
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloys ◽  
Orthopedic Implants ◽  
The Body ◽  
Alloying Elements ◽  
Medical Applications ◽  
Biodegradable Implants ◽  
Metallurgical Characterization

The magnesium alloys has been intensively studied for their suitable mechanical properties, excellent biocompatibility and their ability to biodegrade in biological environments. Although magnesium biodegradable implants possess many desirable properties, it is important that the alloy is able to be tolerated by the body- the constitutional elements of magnesium-based alloys should be toxic free. In this study two binary magnesium alloys Mg-Ca0,8 and Mg-Ca1,8 were experimentally obtained by casting and was characterized in order to investigate the microstructure, mechanical properties and how alloying elements influenced the characteristics of this new alloys potentially used for orthopedic implants.

Production and Characterization of Hydroxyapatite-Zirconia Composites

2012 ◽  
Vol 31 (6) ◽  
pp. 749-753 ◽  
Author(s):  
Melis Ozmen ◽  
Ipek Akin ◽  
Muzeyyen Marsoglu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Sintering Temperature ◽  
Medical Applications ◽  
Mineral Component ◽  
Human Teeth ◽  
Zirconia Composites ◽  
Different Temperatures

AbstractHydroxyapatite (HA) ceramics are used extensively in different medical applications, such as biomaterial for repair or replacement of bone tissues since it resembles mineral component of bone and teeth. However, HA exhibits low fracture toughness due to its lack of strength and brittleness, thereby providing an obstacle to its application in implants that must withstand to high loads. In this study, HA was synthesized from human teeth by using a single calcinations method. Hydroxyapatite powders were mixed with different amounts of zirconia. The composites were sintered at different temperatures and characterized in terms of mechanical properties and the optimum sintering temperature was determined for good mechanical properties.

Thermally-Induced Change in the Relaxation Behavior of Skin Tissue

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
F. Xu ◽  
T. J. Lu ◽  
K. A. Seffen
Keyword(s):  
Great Influence ◽  
Quantitative Relationship ◽  
Relaxation Behavior ◽  
Bioheat Transfer ◽  
Skin Tissue ◽  
Viscoelastic Parameter ◽  
Thermally Induced ◽  
Quantitative Studies ◽  
Temperature Levels

Skin biothermomechanics is highly interdisciplinary, involving bioheat transfer, burn damage, biomechanics, and physiology. Characterization of the thermomechanical behavior of skin tissue is of great importance and can contribute to a variety of medical applications. However, few quantitative studies have been conducted on the thermally-dependent mechanical properties of skin tissue. The aim of the present study is to experimentally examine the thermally-induced change in the relaxation behavior of skin tissue in both hyperthermal and hypothermic ranges. The results show that temperature has great influence on the stress-relaxation behavior of skin tissue under both hyperthermal and hypothermic temperatures; the quantitative relationship that has been found between temperature and the viscoelastic parameter (the elastic fraction or fractional energy dissipation) was temperature dependent, with greatest dissipation at high temperature levels.

scholarly journals Rheological Characterization of Next-Generation Ballistic Witness Materials for Body Armor Testing

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 447
Author(s):  
Ran Tao ◽  
Kirk Rice ◽  
Anicet Djakeu ◽  
Randy Mrozek ◽  
Shawn Cole ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Temperature Sensitivity ◽  
Thermomechanical Behavior ◽  
Oscillatory Shear ◽  
Body Armor ◽  
Resistance Testing ◽  
Rheological Characterization ◽  
Ballistic Performance ◽  
Small Amplitude Oscillatory Shear

Roma Plastilina No. 1 (RP1), an artist modeling clay that has been used as a ballistic clay, is essential for evaluation and certification in standards-based ballistic resistance testing of body armor. It serves as a ballistic witness material (BWM) behind the armor, where the magnitude of the plastic deformation in the clay after a ballistic impact is the figure of merit (known as “backface signature”). RP1 is known to exhibit complex thermomechanical behavior that requires temperature conditioning and frequent performance-based evaluations to verify that its deformation response satisfies requirements. A less complex BWM formulation that allows for room-temperature storage and use as well as a more consistent thermomechanical behavior than RP1 is desired, but a validation based only on ballistic performance would be extensive and expensive to accommodate the different ballistic threats. A framework of lab-scale metrologies for measuring the effects of strain, strain rate, and temperature dependence on mechanical properties are needed to guide BWM development. The current work deals with rheological characterization of a candidate BWM, i.e., silicone composite backing material (SCBM), to understand the fundamental structure–property relationships in comparison to those of RP1. Small-amplitude oscillatory shear frequency sweep experiments were performed at temperatures that ranged from 20 °C to 50 °C to map elastic and damping contributions in the linear elastic regime. Large amplitude oscillatory shear (LAOS) experiments were conducted in the non-linear region and the material response was analyzed in the form of Lissajous curve representations with the values of perfect plastic dissipation ratio reported to identify the degree of plasticity. The results show that the SCBM exhibits dynamic properties that are similar in magnitude to those of temperature-conditioned RP1, but with minimal temperature sensitivity and weaker frequency dependence than RP1. Both SCBM and RP1 are identified as elastoviscoplastic materials, which is particularly important for accurate determination of backface signature in body armor evaluation. The mechanical properties of SCBM show some degree of aging and work history effects. The results from this work demonstrate that the rheological properties of SCBM, at small and large strains, are similar to RP1 with substantial improvements in BWM performance requirements in terms of temperature sensitivity and thixotropy.

Microstructural and fractographic characterization of B4C-Al cermets tested under dynamic and static loading

1989 ◽  
Vol 47 ◽  
pp. 562-563
Author(s):  
Gyeung Ho Kim ◽  
Mehmet Sarikaya ◽  
D. L. Milius ◽  
I. A. Aksay
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Static Loading ◽  
Carbon Deposition ◽  
Full Density ◽  
Unique Combination ◽  
Strong Component ◽  
Reaction Products

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.

Characterization of interfaces in CVD-coated nicalon fiber-reinforced SiC

1989 ◽  
Vol 47 ◽  
pp. 556-557
Author(s):  
K.L. More ◽  
R.A. Lowden
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Frictional Stress ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Carbon Coated ◽  
Fiber Matrix

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.

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