Thermal Injury from Mastoid Bone Burrs

1978 ◽  
Vol 87 (1) ◽  
pp. 43-49 ◽  
Author(s):  
William H. Call
Keyword(s):  
Contact Area ◽  
Thermal Injury ◽  
Rotation Speed ◽  
Applied Pressure ◽  
Haversian Canal ◽  
Operative Field ◽  
Continuous Irrigation ◽  
Area Increase ◽  
Surface Contact Area ◽  
Tissue Grafts

Marked bone temperature elevations and surface osteocyte necrosis result from cutting and diamond burrs used without continuous irrigation. Temperatures generated may injure the facial nerve even if drilling is carried on a millimeter or more distant from the nerve. Irrigation of the operative field maintains bone and nerve temperatures at safe levels. Cutting and diamond burrs obey different thermodynamic principles. Higher rotation speeds, greater applied pressures and greater surface contact area increase cutting burr thermogenesis. Burrs with more flutes generate greater heat than those with fewer flutes. Diamond burr heat generation varies in proportion to applied pressure, but is independent of rotation speed or contact area. Haversian canal blood vessels do not contribute to postoperative revascularization. Rather, vessels immigrate from adjacent intact periosteum, penetrating arterioles and exposed marrow. Surface thermal injury does not impede revascularization and should not impair the healing of tissue grafts applied to the bone surface.

scholarly journals Influence of variable cutting surface contact area on the components of cutting forces and accuracy

2021 ◽  
pp. 20-24
Author(s):  
Esreb DZHEMILOV
Keyword(s):  
Contact Area ◽  
Cutting Forces ◽  
Applied Pressure ◽  
Contact Areas ◽  
Cutting Surface ◽  
Surface Contact ◽  
Surface Contact Area

The article discusses the process of diamond honing of conical holes. The purpose of the article is to identify the dependence of power in the process of cutting and the effect of changing the contact areas of the components of the cutting forces. The experiments were carried out on a developed installation to determine the cutting ability of diamond honing stones. Depen- dences of linear removal of steel 50 and steel 45 on the applied pressure have been established. Based on the data obtained, it can be concluded that if the value of the Py index goes beyond the limits of pure contact, then this leads to the seizure of surfaces and a deterioration in the quality of processing.

GRAIN REFINEMENT AND MICROSTRUCTURE EVOLUTION IN ALUMINUM A2618 ALLOY BY HIGH-PRESSURE TORSION

2016 ◽  
Vol 78 (6-9) ◽  
Author(s):  
Intan Fadhlina Mohamed ◽  
Seungwon Lee ◽  
Kaveh Edalati ◽  
Zenji Horita ◽  
Shahrum Abdullah ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Grain Refinement ◽  
Room Temperature ◽  
Rotation Speed ◽  
High Pressure Torsion ◽  
Applied Pressure ◽  
Saturation Level ◽  
Microstructural Refinement ◽  
Average Grain Size

This work presents a study related to the grain refinement of an aluminum A2618 alloy achieved by High-Pressure Torsion (HPT) known as a process of Severe Plastic Deformation (SPD). The HPT is conducted on disks of the alloy under an applied pressure of 6 GPa for 1 and 5 turns with a rotation speed of 1 rpm at room temperature. The HPT processing leads to microstructural refinement with an average grain size of ~250 nm at a saturation level after 5 turns. Gradual increases in hardness are observed from the beginning of straining up to a saturation level. This study thus suggests that hardening due to grain refinement is attained by the HPT processing of the A2618 alloy at room temperature.

scholarly journals Strontium Oxide Deposited onto a Load-Bearable and Porous Titanium Matrix as Dynamic and High-Surface-Contact-Area Catalysis for Transesterification

Nanomaterials ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 973 ◽  
Author(s):  
Han Lee ◽  
Jiunn-Der Liao ◽  
Mu Lee ◽  
Bernard Liu ◽  
Wei-En Fu ◽  
...  
Keyword(s):  
Contact Area ◽  
Porous Matrix ◽  
Porous Titanium ◽  
Transesterification Reaction ◽  
Biodiesel Production ◽  
Strontium Oxide ◽  
Chemical Structures ◽  
Surface Contact ◽  
Surface Contact Area ◽  
Highly Porous

Strontium oxide (SrO) deposited onto a porous titanium (Ti)-based scaffold (P-Ti) is a promising and novel approach for high-throughput transesterification. Notably, a highly porous and calcinated scaffold provides a load-bearable support for a continuous process, while the calcinated SrO catalyst, as it is well distributed inside the porous matrix, can extend its surface contact area with the reactant. In this work, the formation of transesterification reaction with the conversion and production of olive oil to biodiesel inside the porous matrix is particularly examined. The as-designed SrO-coated porous titanium (Ti)-based scaffold with 55% porosity was prepared via a hydrothermal procedure, followed by a dip coating method. Mechanical tests of samples were conducted by a nanoindentator, whereas the physical and chemical structures were identified by IR and Raman Spectroscopies. The results implied that SrO catalysts can be firmly deposited onto a load-bearable, highly porous matrix and play an effective role for the transesterification reaction with the oil mass. It is promising to be employed as a load-bearable support for a continuous transesterification process, such as a process for batch or continuous biodiesel production, under an efficient heating source by a focused microwave system.

scholarly journals Development of Pant-Type Harness with Fabric Air-Pocket for Pain Relief

2019 ◽  
Vol 9 (9) ◽  
pp. 1921
Author(s):  
Dongwoo Nam ◽  
Miyeon Kwon ◽  
Juhea Kim ◽  
Bummo Ahn
Keyword(s):  
Contact Area ◽  
Peak Pressure ◽  
Applied Pressure ◽  
The Body ◽  
Area Measurement ◽  
Medical Applications ◽  
Air Pocket ◽  
Long Time ◽  
Developed Pressure ◽  
Air Pockets

Harnesses can be used in various applications, such as entertainment, rescue operations, and medical applications. Because users are supported on the harness for a long time, they should feel comfortable wearing the harnesses. However, existing commercial harnesses are uncomfortable to wear and cause continuous serious pain. Therefore, in this study, a new pant-type harness with a fabric air pocket to reduce the applied pressure on the body, especially in the groin, is proposed. Keeping this in mind, we have designed and developed the pant-type harness. In addition, we performed pressure and contact area measurement experiments using the harness developed, pressure sensor, and a human mannequin. Peak and mean pressures and contact areas near the groin and waist were measured in the experiments. From the results, when air is injected in the air pockets, the peak pressure and contact area near the waist increased, and the peak pressure near the groin decreased. This means that the pressure applied on the human mannequin near the groin reduces because of the increased contact area near the waist, which is achieved by multi-layered air pockets. In this study, we proposed the optimal design of a novel pant-type harness that can address the limitations of existing harnesses. The proposed harness can be used for a prolonged time in applications, such as virtual reality entertainment, rescue operations, and rehabilitation.

Dynamic Responses of a Cracked Gas-Bearing Spindle

2004 ◽  
Author(s):  
Bo-Wun Huang ◽  
Jao-Hwa Kuang
Keyword(s):  
Rotation Speed ◽  
Crack Depth ◽  
Applied Pressure ◽  
Equation Of Motion ◽  
Dynamic Responses ◽  
Bernoulli Beam ◽  
Spindle System ◽  
Depth Rotation ◽  
Euler Bernoulli Beam ◽  
Gas Bearing

The dynamic response of a cracked gas-bearing spindle system is studied in this work. A round Euler-Bernoulli beam is used to approximate the spindle system. The stiffness effect of the gas bearing spindle is considered as massless springs and the Hamilton principle is employed to derive the equation of motion for the spindle system. The effects of crack depth, rotation speed and air applied pressure on the dynamic characteristics of a rotating gas-bearing spindle system are studied.

Creep Relaxation of an Elastic–Perfectly Plastic Hemisphere in Fully Plastic Contact

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Andreas Goedecke ◽  
Randolf Mock
Keyword(s):  
Creep Behavior ◽  
Contact Area ◽  
Geometrical Parameters ◽  
Second Phase ◽  
Perfectly Plastic ◽  
Area Increase ◽  
Accelerated Creep ◽  
Material Creep ◽  
Evolution Laws ◽  
Elastic Perfectly Plastic

A set of finite element simulations was performed to analyze the creep behavior of an elastic–perfectly plastic hemisphere in contact with a rigid flat. This study focuses on the time-dependent stress relaxation of a fully plastic asperity. Assuming a Garofalo (hyperbolic sine) type material creep law, the asperity shows two distinct phases of relaxation. In the first phase, the asperity creeps with an accelerated creep rate and shows a contact area increase similar to that of a cylindrical geometry. In the second phase, no contact area change can be measured and the asperity creeps with a slower rate. Empirical evolution laws for the asperity creep behavior are presented, analyzing the influence of both material and geometrical parameters. The results are interpreted in terms of transient friction.

Studies on Head/Disc Contact Area Increase During Contact Start/Stop and Continuous Drag Testing of Thin Film Discs

1993 ◽  
Vol 36 (1) ◽  
pp. 1-10 ◽  
Author(s):  
R. Koka ◽  
T. Pitchford ◽  
M. Jesh ◽  
D. Egbert
Keyword(s):  
Thin Film ◽  
Contact Area ◽  
Area Increase
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