On the Physics of the Bone Fracture
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10-1 CHAPTER 10 DEFORMATION 10.1 Stress-Strain Diagrams And
EN380 Naval Materials Science and Engineering Course Notes, U.S. Naval Academy CHAPTER 10 DEFORMATION 10.1 Stress-Strain Diagrams and Material Behavior 10.2 Material Characteristics 10.3 Elastic-Plastic Response of Metals 10.4 True stress and strain measures 10.5 Yielding of a Ductile Metal under a General Stress State - Mises Yield Condition. 10.6 Maximum shear stress condition 10.7 Creep Consider the bar in figure 1 subjected to a simple tension loading F. Figure 1: Bar in Tension Engineering Stress () is the quotient of load (F) and area (A). The units of stress are normally pounds per square inch (psi). = F A where: is the stress (psi) F is the force that is loading the object (lb) A is the cross sectional area of the object (in2) When stress is applied to a material, the material will deform. Elongation is defined as the difference between loaded and unloaded length ∆푙 = L - Lo where: ∆푙 is the elongation (ft) L is the loaded length of the cable (ft) Lo is the unloaded (original) length of the cable (ft) 10-1 EN380 Naval Materials Science and Engineering Course Notes, U.S. Naval Academy Strain is the concept used to compare the elongation of a material to its original, undeformed length. Strain () is the quotient of elongation (e) and original length (L0). Engineering Strain has no units but is often given the units of in/in or ft/ft. ∆푙 휀 = 퐿 where: is the strain in the cable (ft/ft) ∆푙 is the elongation (ft) Lo is the unloaded (original) length of the cable (ft) Example Find the strain in a 75 foot cable experiencing an elongation of one inch. -
Impact of Flow Velocity on Surface Particulate Fouling - Theoretical Approach
Journal of American Science 2012;8(9) http://www.jofamericanscience.org Impact of Flow velocity on Surface Particulate Fouling - Theoretical Approach Mostafa M. Awad Mech. Power Eng. Dept., Faculty of Engineering, Mansoura University, Egypt [email protected] Abstract: The objective of this research is to study the effect of flow velocity on surface fouling. A new theoretical approach showing the effect of flow velocity on the particulate fouling has been developed. This approach is based on the basic fouling deposition and removal processes. The present results show that, the flow velocity has a strong effect on both the fouling rate and the asymptotic fouling factor; where the flow velocity affects both the deposition and removal processes. Increasing flow velocity results in decreasing both of the fouling rate and asymptotic values. Comparing the obtained theoretical results with available experimental ones showed good agreement between them. The developed model can be used as a very useful tool in the design and operation of the heat transfer equipment by controlling the parameters affecting fouling processes. [Mostafa M. Awad. Impact of Flow velocity on Surface Particulate Fouling - Theoretical Approach. J Am Sci 2012;8(9):442-449]. (ISSN: 1545-1003). http://www.jofamericanscience.org. 62 Keywords: Surface fouling, flow velocity, particle sticking, mass transfer. 1. Introduction increasing the flow velocity. They also found that the Fouling of heat transfer surface is defined as the asymptotic fouling factor is very sensitive to the flow accumulation of unwanted material on the heat transfer velocity especially at low flow velocities where this surface. This accumulation deteriorates the ability of sensitivity decreases with increasing flow velocity. -
Delayed Massive Hemothorax Requiring
Clin Exp Emerg Med 2018;5(1):60-65 https://doi.org/10.15441/ceem.16.190 Case Report Delayed massive hemothorax requiring eISSN: 2383-4625 surgery after blunt thoracic trauma over a 5-year period: complicating rib fracture with sharp edge associated with diaphragm injury Received: 26 September 2017 Revised: 28 January 2018 Sung Wook Chang, Kyoung Min Ryu, Jae-Wook Ryu Accepted: 20 February 2018 Trauma Center, Department of Thoracic and Cardiovascular Surgery, Dankook University Hospital, Cheonan, Korea Correspondence to: Jae-Wook Ryu Department of Thoracic and Cardiovascular Surgery, Dankook Delayed massive hemothorax requiring surgery is relatively uncommon and can potentially be University Hospital, 201 Manghyang-ro, Dongnam-gu, Cheonan 31116, Korea life-threatening. Here, we aimed to describe the nature and cause of delayed massive hemotho- E-mail: [email protected] rax requiring immediate surgery. Over 5 years, 1,278 consecutive patients were admitted after blunt trauma. Delayed hemothorax is defined as presenting with a follow-up chest radiograph and computed tomography showing blunting or effusion. A massive hemothorax is defined as blood drainage >1,500 mL after closed thoracostomy and continuous bleeding at 200 mL/hr for at least four hours. Five patients were identified all requiring emergency surgery. Delayed mas- sive hemothorax presented 63.6±21.3 hours after blunt chest trauma. All patients had superfi- cial diaphragmatic lacerations caused by the sharp edge of a broken rib. The mean preoperative chest tube drainage was 3,126±463 mL. We emphasize the high-risk of massive hemothorax in patients who have a broken rib with sharp edges. -
Accuracy of Diagnosis of Distal Radial Fractures by Ultrasound Ahmad Saladdin Sultan, Muddather Abdul Aziz, Yakdhan Z
The Egyptian Journal of Hospital Medicine (October 2017) Vol. 69 (8), Page 3115-3122 Accuracy of Diagnosis of Distal Radial Fractures by Ultrasound Ahmad Saladdin Sultan, Muddather Abdul Aziz, Yakdhan Z. Alsaleem Mosul Teaching Hospital, Emergency Medicine Department, Mosul, Iraq Corresponding author: Ahmad Saladdin <[email protected] ABSTRACT Background: although distal radial fracture account up to 20% of all fractures, it forms the most common fracture in upper extremities. Distal radial fracture has six types the most common one is Colle's fracture. The gold standard for diagnosis of distal radial fracture is conventional radiograph. Despite using ultrasound in tendon rupture, localizing foreign bodies, ultrasound started to be used for diagnosing bone fracture especially distal radius. Aim of the work: this study aimed to detect the accuracy of ultrasound in the diagnosis of distal radial fracture. Patients and methods: this was a selective prospective case series study in the Emergency Department, Al-Jumhoori Teaching Hospital,78 patients were included in this study, their age ranged between 6-45 years with mean age 17.1. 59 were males and 19 females. Duration of the study was one year (January2013 - January 2014). Results: by analyzing data of 78 patients for distal radial fracture ultrasound and comparing the results with the gold standard conventional radiograph we found that sensitivity of ultrasound in detecting fracture was 95.5%, specificity 100%, accuracy 96.15%, positive predictive value 100% and negative predictive value 80%. Conclusion: results of the current work demonstrated that ultrasound can be considered as a promising alternative to routine radiograph in diagnosis of the distal radial fractures and the horizon still open for further studies of use of ultrasound in diagnosis of other types of fractures. -
Ductile Brittle Transition
XIX. EVALUATION OF DUCTILE/BRITTLE FAILURE THEORY, DERIVATION OF THE DUCTILE/BRITTLE TRANSITION TEMPERATURE Introduction The ductile/brittle transition for failure with all of its implications and ramifications is one of the most widely observed and universally acknowledged physical effects in existence. Paradoxically though it also is one of the least understood of all the physical properties and physical effects that are encountered in the world of materials applications. Critical judgments are made on the basis of experience only, purely heuristic and intuitive. The resolution of the ductile/brittle transition into a physically meaningful and useful mathematical form has always been problematic and elusive. It often has been suggested that such a development is highly unlikely. The rigorous answer to this question remains and continues as one of the great scientific uncertainties, challenges. The long time operational status of ductile/brittle behavior has reduced to a statement of the strain at failure in uniaxial tension. If the strain at failure is large, the material is said to be ductile. If the strain at failure is small, it is brittle. Loose and uncertain though this is, it could be general, even complete, if the world were one-dimensional. But the physical world is three-dimensional and in stress space it is six or nine dimensional. Even more complicating, some of the stress components are algebraic. So the problem is large and difficult, perhaps immensely large and immensely difficult. To even begin to grapple with the ductile/brittle transition one must first have a firm grasp on a general and basic theory of failure. -
Little Book of Dynamic Buckling
. Little Book of Dynamic Buckling Herbert E. Lindberg September 2003 LCE Science/Software 1 Preface A graduate program in mechanics (often part of aero/astronautical, civil or mechanical engineering) generally includes a short series on elastic stability of structures. Within the confines of available time, focus is on stability under static loading, with dynamic loading from earthquakes, aerodynamics, impact and so on touched on only briefly except for students with thesis topics in these areas. This short book is intended as a brief introduction to dynamic buckling that can be covered in the limited time available in a broad graduate program. It is small and inexpensive enough that the student can own his or her own copy, rather than simply taking notes during lectures extracted by the teacher from the several full-size texts available on this topic, including one by the present author. The book introduces concepts of dynamic buckling in the simplest possible context for each phenomenon. The phenomena treated all fall under the definition of dynamic stability of structures under time-varying parametric loading. The goal is met by treating simple bars under axial loads, rings under lateral pulse loads, and cylindrical shells under radial and axial loads. The present document includes only a general introduction and then comprehensive presentation of theory and experimental data for bars under static and impact loads. Sections on rings and shells will be made available as orders are received. In all cases motion is precipitated by inevitable imperfections in structural shape. Sometimes these appear as a simple parameter, as in the eccentricity of impact. -
Treatment of Common Hip Fractures: Evidence Report/Technology
This report is based on research conducted by the Minnesota Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (Contract No. HHSA 290 2007 10064 1). The findings and conclusions in this document are those of the authors, who are responsible for its content, and do not necessarily represent the views of AHRQ. No statement in this report should be construed as an official position of AHRQ or of the U.S. Department of Health and Human Services. The information in this report is intended to help clinicians, employers, policymakers, and others make informed decisions about the provision of health care services. This report is intended as a reference and not as a substitute for clinical judgment. This report may be used, in whole or in part, as the basis for the development of clinical practice guidelines and other quality enhancement tools, or as a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied. Evidence Report/Technology Assessment Number 184 Treatment of Common Hip Fractures Prepared for: Agency for Healthcare Research and Quality U.S. Department of Health and Human Services 540 Gaither Road Rockville, MD 20850 www.ahrq.gov Contract No. HHSA 290 2007 10064 1 Prepared by: Minnesota Evidence-based Practice Center, Minneapolis, Minnesota Investigators Mary Butler, Ph.D., M.B.A. Mary Forte, D.C. Robert L. Kane, M.D. Siddharth Joglekar, M.D. Susan J. Duval, Ph.D. Marc Swiontkowski, M.D. -
On Impact Testing of Subsize Charpy V-Notch Type Specimens*
DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsi• bility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Refer• ence herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recom• mendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. ON IMPACT TESTING OF SUBSIZE CHARPY V-NOTCH TYPE SPECIMENS* Mikhail A. Sokolov and Randy K. Nanstad Metals and Ceramics Division OAK RIDGE NATIONAL LABORATORY P.O. Box 2008 Oak Ridge, TN 37831-6151 •Research sponsored by the Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, under Interagency Agreement DOE 1886-8109-8L with the U.S. Department of Energy under contract DE-AC05-84OR21400 with Lockheed Martin Energy Systems. The submitted manuscript has been authored by a contractor of the U.S. Government under contract No. DE-AC05-84OR21400. Accordingly, the U.S. Government retains a nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes. Mikhail A. -
RAM Guard Column Protector
by Ridg-U-Rak Steel Reinforced Rubber Guard Superior Column Protection RAMGuard™ provides superior rack column protection with its patented Rubber Armored Metal design. Molded of energy absorbing rubber with a “U-shaped” steel insert and force distributing rubber voids, RAMGuard absorbs significantly more energy during impact than most column protection devices offered today. RAMGuard Advantages The 12” high RAMGuard snaps onto • Protects rack structures from frontal, angled and side impacts rolled or structural steel columns • Significantly lowers impact damage to pallet rack columns 3” wide and up to 3” deep. • Requires no hardware or straps to retain the guard on column • Endures many impacts with no loss of performance • Significantly outperforms most plastic guards commonly used today Ph: 814.347.1174 • Email: [email protected] • Website: TheRAMGuard.com RG-2 RAMGuard Design Maximum Impact Resistance by Design Molded of Energy There is a wide range of products designed to Absorbing Rubber help protect pallet rack columns from the everyday abuses that commonly occur in busy warehouse U-Shaped environments. These products include steel Steel Insert reinforced columns, slant-back or offset frames, floor-mounted steel guards, bumpers, barriers and after market attachable guards. Each of these serves a purpose for different applications. Aftermarket attachable guards have a variety of applications ranging from small plants with high traffic areas to large facilities where it is critical to reduce the time and cost of replacing damaged uprights… and everything in between. There are many types, kinds and sizes of guards on the market today, but none like the RAMGuard. After nearly two years of development, testing and proto-type designs, the new patented RAMGuard delivers the greatest impact resistance available in aftermarket snap-on or strap-on column guards. -
Addressing Stress Corrosion Cracking in Turbomachinery Industry.Indd
Addressing Stress Corrosion Cracking in the Turbomachinery Industry Stress Corrosion Cracking is a common problem affecting turbomachinery components such as rotor discs, steam turbine blades and compressor impellers, and is a major factor driving component repair. This type of cracking may lead to catastrophic failures which result in unplanned down time and expensive repairs. A comprehensive root cause failure analysis is always needed to determine and confirm the root causes. Based on the findings of the analysis, different methods can be used to alleviate the cause of stress corrosion cracking. The design of the component, operating environment and other factors should be considered when selecting a method to mitigate stress corrosion cracking. Introduction Stress corrosion cracking (SCC) is a failure that occurs in a Figure 1 shows an SEM image of a fracture surface exhibiting part when the following conditions are met: intergranular mode of propagation on an integral disk of a steam turbine rotor. 1. An alloy is susceptible to stress corrosion cracking 2. Corrosive environment Care should be exercised when attributing an intergranular 3. Sufficient level of stress mode of propagation to SCC since there are other failure mechanisms (such as creep) that lead to an intergranular At Sulzer we have analyzed multiple cases of stress corrosion mode of failure. cracking on turbomachinery parts such as steam turbine rotors, steam turbine blades, shroud bands and compressor Branching of a crack is another common characteristic of impellers. SCC and optical metallography through a fracture/crack will help identify this feature. Both modes of propagation Sometimes we work with equipment where failures have can exhibit crack branching. -
Evaluation of Ductile/Brittle Failure Theory and Derivation of the Ductile/Brittle Richard M
Evaluation of Ductile/Brittle Failure Theory and Derivation of the Ductile/Brittle Richard M. Christensen Professor Research Emeritus Transition Temperature Aeronautics and Astronautics Department, Stanford University, A recently developed ductile/brittle theory of materials failure is evaluated. The failure Stanford, CA 94305 theory applies to all homogeneous and isotropic materials. The determination of the duc- e-mail: [email protected] tile/brittle transition is an integral and essential part of the failure theory. The evaluation process emphasizes and examines all aspects of the ductile versus the brittle nature of failure, including the ductile limit and the brittle limit of materials’ types. The failure theory is proved to be extraordinarily versatile and comprehensive. It even allows deriva- tion of the associated ductile/brittle transition temperature. This too applies to all homo- geneous and isotropic materials and not just some subclass of materials’ types. This evaluation program completes the development of the failure theory. [DOI: 10.1115/1.4032014] Keywords: ductile, brittle, ductile/brittle transition, ductile/brittle transition temperature, materials failure, failure theory Introduction There is one exception to this quite dire state of affairs and it is the case of what are commonly called very ductile metals. The The ductile/brittle transition for failure with all of its implica- flow of dislocations embodies the essence of ductility and it has tions and ramifications is one of the most widely observed and been a very active area of study for a great many years. The many universally acknowledged physical effects in existence. Paradoxi- related papers on the ductile/brittle transition in ductile metals cally, it is also one of the least understood of all the physical prop- generally examine the emission of dislocations at crack tips to see erties and physical effects that are encountered in the world of how local conditions can influence this. -
Impact of Hard Fouling on the Ship Performance of Different Ship Forms
Journal of Marine Science and Engineering Article Impact of Hard Fouling on the Ship Performance of Different Ship Forms Andrea Farkas 1, Nastia Degiuli 1,*, Ivana Marti´c 1 and Roko Dejhalla 2 1 Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Luˇci´ca5, 10000 Zagreb, Croatia; [email protected] (A.F.); [email protected] (I.M.) 2 Faculty of Engineering, University of Rijeka, Vukovarska ulica 58, 51000 Rijeka, Croatia; [email protected] * Correspondence: [email protected]; Tel.: +38-516-168-269 Received: 3 September 2020; Accepted: 24 September 2020; Published: 26 September 2020 Abstract: The successful optimization of a maintenance schedule, which represents one of the most important operational measures for the reduction of fuel consumption and greenhouse gas emission, relies on accurate prediction of the impact of cleaning on the ship performance. The impact of cleaning can be considered through the impact of biofouling on ship performance, which is defined with delivered power and propeller rotation rate. In this study, the impact of hard fouling on the ship performance is investigated for three ship types, keeping in mind that ship performance can significantly vary amongst different ship types. Computational fluid dynamics (CFD) simulations are carried out for several fouling conditions by employing the roughness function for hard fouling into the wall function of CFD solver. Firstly, the verification study is performed, and the numerical uncertainty is quantified. The validation study is performed for smooth surface condition and, thereafter, the impact of hard fouling on resistance, open water and propulsion characteristics is assessed.