In linguistics , stress is the relative emphasis that may be given to certain syllable s in a word, or to certain ... Further Timing linguistics English language English is a stress timed language that is, stressed syllables ... Phonology Secondary stress Syllable Timing linguistics Timing Vowel reduction Weak form and strong ... Feet and Metrical Stress The Cambridge Handbook of Phonology Suprasegmentals DEFAULTSORT StressLinguistics Category Phonetics Category Stresslinguistics Category Phonology Category Poetic rhythm ar ... The ways stress manifests itself in the speech stream are highly language dependent. In some languages ... accent . Stress may be characterized by more than one of these characteristics. Further, stress may ... signals of stressed and unstressed syllables may be minimal. In English, stress is most dramatically ... tomorrow? No, it s dinner tomorrow. In it, the stress related acoustic differences between the syllables .... ref M. E. Beckman, Stress and Non Stress Accent, Dordrecht Foris 1986 ISBN 90 6765 243 1 ref ref R. Silipo and S. Greenberg, Automatic Transcription of Prosodic Stress for Spontaneous English ... measurable, and strongly correlated with pitch, but not quite the same thing. Stress can also be put ... . I took it some other day. The possibilities for stress in tone language s is an area of ongoing research, but stress like patterns have been observed in Mandarin Chinese. ref Kochanski, G., Shih, C ... dynamic stress is accompanied by greater respiratory system respiratory force, it does not mean ... iambic L L, L H, H demarcative function fixed word edge culminativity lexical words have single stress binary vs ternary Some languages have fixed stress. The stress is placed always on a given syllable, as in Czech language Czech , Finnish language Finnish and Hungarian language Hungarian stress always on the first syllable or Quechua language Quechua and Polish language Polish stress always on the penult ... language Macedonian see Stress in Macedonian language . Other languages have stress placed ... more details
wiktionarypar stressStress may refer to Mechanical Stress mechanics , the average amount of force exerted per unit area. It is the internal resistance a material offers to being deformed and is measured in terms of the applied load. The effects of mechanical stress on a polymer can be measured using dynamic mechanical analysis . Compressive stress , the stress applied to materials resulting in their compaction. It is the ability of a material to resist being crushed. Tensile stress also referred to as tension is the stress state leading to expansion. Yield engineering Yield stress , the stress at which a material begins to deform plastically. Biological Stress biology , physiological or psychological stress some types include Chronic stress , persistent stress which can lead to illness and mental disorder Eustress , positive stress that can lead to improved long term functioning Workplace stress , stress caused by employment. Geological Compression geology , the set of stresses directed toward the center of a rock mass Shear geology , the response of a rock to deformation usually by compressive stress and forms particular textures Tension geology , occurs when a rock is pulled apart in two opposite directions Music Accent music Stress band , an early 1980s melodic rock band from San Diego Stress Neo Psychedelic band , from the late 1980s Stress , a song by French band Justice, from album Stress , a song by Odd B rre , the entrant representing Norway at the Eurovision Song Contest 1968 Other Stress game , card game Stresslinguistics , phonological use of prominence in language Stress journal , a medical journal published by Informa plc Stress The Unit Stress The Unit , an episode of the television series The Unit disambig ar bs Stres de Stress Begriffskl rung fr Stress homonymie ko it Stress he ja simple Stress sk Stres sr uk ... more details
Infobox single Name No Stress Cover No stress CD maxi .jpg Border Caption Artist Laurent Wolf Album Wash ... Last single Another Brick br 2006 This single No Stress br 2008 Next single Wash My World br ... No Stress is the name of a 2008 song recorded by the French House music house producer and DJ ... language French accessdate 21 January 2009 ref It remained on the chart top 100 for 37 weeks. No Stress ... and totaled 72 weeks in the top 100. Track listings CD single Tracklist title1 No Stress note1 length1 3 26 CD maxi Tracklist title1 No Stress note1 radio edit length1 3 22 title2 No Stress note2 Anton Wick remix length2 7 28 title3 No Stress note3 Ortega & Gold remix length3 7 09 title4 Columbia note4 length4 5 10 12 maxi Tracklist title1 No Stress note1 original club mix length1 6 59 title2 No Stress note2 Anton Wick remix length2 7 28 title3 No Stress note3 Ortega & Gold remix length3 7 09 title4 No Stress note4 Anton Wick elektra remix length4 7 08 Digital download Tracklist title1 No Stress note1 Zen Acoustic version length1 3 26 title2 No Stress note2 radio edit length2 3 21 title3 No Stress note3 Anton Wick remix length3 7 29 title4 No Stress note4 Ortega & Gold remix length4 3 08 ... sortable Chart 2008 Peak br position Belgian Flanders Singles Chart ref cite web title No Stress ... ref cite web title No Stress , Belgian Wallonia Singles Chart url http www.ultratop.be fr showitem.asp ... Czech IFPI Chart ref cite web title No Stress , Czech IFPI Chart url http www.ifpicr.cz hitparada index.php ... title No Stress , Dutch Singles Chart url http acharts.us song 34797 publisher Acharts accessdate 24 ... Singles Chart ref cite web title No Stress , French Singles Chart url http lescharts.com showitem.asp ... Mahasz Hungarian Dance Chart ref cite web title No Stress , Hungarian Top40 Dance Chart url http mahasz.hu ... No Stress , Italian Singles Chart url http italiancharts.com showitem.asp?interpret Laurent Wolf&titel ... 18 Russian Airplay Chart ref cite web title No Stress , Russian Singles Chart url http top40 charts.com ... more details
about the field of study the journal Linguistics journal linguisticsLinguistics is the scientific study of human language . ref Cite book title Linguistics An Introduction to Linguistic Theory last Fromkin ... 0631197117 page 3 ref ref cite book title Elements of General Linguistics last Martinet first Andr authorlink Andr Martinet others Tr. Elisabeth Palmer Studies in General Linguistics, vol. i. location London publisher Faber year 1960 page 15 ref ref Cite book title On Language and Linguistics first ... title Linguistics and ethnology journal Southwestern Journal of Anthropology volume 4 pages 140 47 year 1948 last Greenberg first Joseph authorlink Joseph Greenberg ref Linguistics can be broadly broken ... of rules followed by the speakers or hearers of a language. It encompasses morphology linguistics morphology ... from these words , and phonology sound systems . Phonetics is a related branch of linguistics ... and perceived. The study of language Meaning linguistics meaning is concerned with how languages ... context includes evolutionary linguistics , which considers the origins of language historical linguistics ... of texts and conversations. Although linguistics is the scientific study of language, a number ... theory Literary theorists study the use of language in literature . Linguistics additionally draws ... analysis linguistics synchronic analysis , however, this focus has shifted ref Cite book last ..., ref A. Morpurgo Davies Hist. Linguistics 1998 4 I. 22. ref where it was never as popular as it was elsewhere ... linguistics is first attested in 1847. ref name etymonline linguist http www.etymonline.com index.php ..., applies within the field to someone who either studies linguistics or uses linguistic methodologies ... Houghton Mifflin Harcourt year 2000 isbn 978 0395825174 ref Fundamental concerns and divisions Linguistics ... govern how native speakers use language. Linguistics has many sub fields concerned with particular ... linguistics include Phonetics , the study of the physical properties of speech or signed production ... more details
orphan date December 2009 Contrastive stress is the Stresslinguistics stressing of a word or syllable different from its normal accentuation or pronunciation for the purpose of providing contrast or focus from an alternative word or syllable. Examples In the Gettysburg Address given by Abraham Lincoln , the stress given in the words of , by , and for in the sentence of the people, by the people, for the people is used to distinguish the three words as having greater purpose than the common terms. ref http dictionary.reference.com browse contrastive stress ref Reference Reflist Category Phonology Category Phonetics ... more details
Secondary stress or secondary accent obsolete is the weaker of two degrees of Stresslinguisticsstress in the pronunciation of a word the stronger degree of stress is called primary . The help IPA International Phonetic Alphabet symbol for secondary stress is a short vertical line preceding and at the foot ... syllable in a prosodic unit , br which receives additional prosody linguistics prosodic tonic stress ... acute and grave accents for primary and secondary stress pron nci tion . Most languages, if they have stress at all, have only one degree of it on the phonemic level. That is, each syllable has stress or it does not. Many languages have rhythmic stress location of the stress may not be predictable, but once the location of one stressed syllable which may be the primary stress is known, certain syllables before or after can be predicted to also be stressed these may have secondary stress. However, a few languages may have secondary stress that is not predictable, that is, phonemic. English is generally considered to be such a language, but this analysis is problematic. Degrees of stress ... two levels of stress. Secondary stress is important primarily in long words with several syllables before the primary stress, such as c unterint lligence IPA ka nt r. n t l d ns , and after the primary stress in many compound word s, such as c unterf il IPA ka nt r f l . ref The foil of counterfoil is transcribed with secondary stress in Merriam Webster s dictionaries, for example, but not in the Oxford English Dictionary. Both dictionaries assign secondary stress to the counter of counterintelligence. ref Indeed, in some theories English has been described as having three levels of stress ... English with only one degree of stress, as long as unstressed vowel unstressed syllables are phonemically ... phonetic detail and not true phoneme phonemic stress. They report that often the alleged secondary stress ... stress in English or with all stress in other languages. In their analysis, an English syllable ... more details
Stress intensity can refer to Stress intensity factor in fracture mechanics Henri Tresca Tresca effective stress in Yield engineering material yielding . disambig ... more details
Stress test may refer to Stress Test television , an episode of Brandy and Mr Whiskers Stress testing , a form of testing that is used to determine the stability of a given system or entity Stress testing software , determines the robustness of software Contraction stress test Cardiac stress test Bank stress tests of 2009 and 2010 For stress testing of materials, see Fatigue material dab Long comment to avoid being listed on short pages ... more details
Stress tensor may refer to Stress mechanics , in classical physics Stress energy tensor , in relativistic theories Maxwell stress tensor , in electromagnetism See also Stress disambiguation Tensor disambiguation disambig de Spannungstensor he ... more details
Unreferenced date December 2009 Orphan date October 2008 In continuum mechanics , Haigh Westergaard stress space , or simply stress space is a 3 dimensional space in which the three spatial axes represent the three principal stresses for a body subject to Stress physics stress . Functions of the principal stresses, such as the yield function, can be represented by surfaces in stress space . In particular, the surface represented by von Mises stress von Mises yield function is a right circular cylinder, equiaxial to each of the three stress axes. In 2 dimensional models, stress space reduces to a plane and the von Mises yield surface reduces to an ellipse. DEFAULTSORT Stress Space Category Continuum mechanics ... more details
Unreferenced stub auto yes date December 2009 Orphan date February 2009 Radial stress is Stress physics stress towards or away from the central axis of a curved member. br DEFAULTSORT Radial Stress Category Solid mechanics Engineering stub ... more details
refimprove date October 2010 File Stress ball manipulation.jpg thumb A stress ball in use File Turkey stress reliever.jpg thumb A turkey shaped foam rubber stress reliever A stress ball is a malleable toy, usually not more than 7 cm in diameter. It is squeezed in the hand and manipulated by the fingers, ostensibly to either help relieve stress and muscle tension or to exercise the muscles of the hand. There are many types of stress balls. Many are a closed cell polyurethane foam rubber . This type of stress ball is made by injecting the liquid components of the foam into a mold. The resulting chemical reaction creates carbon dioxide bubbles as a byproduct, which in turn creates the foam. ref cite web url http www.stressballs.gb.com info stressfaq.html title Stress Ball FAQs archiveurl http web.archive.org web 20080215101551 http www.stressballs.gb.com info stressfaq.html archivedate Feb. 15, 2008 ref Stress balls, especially those used in physical therapy , can also contain gel of different densities inside a rubber or cloth skin. Another type uses a thin rubber membrane surrounding ... balls similar to a footbag are marketed and used as stress balls. Despite the name, many stress balls are not spherical. Many stress toys are molded in amusing shapes and screen or transfer printed with corporate logos. They are presented to employees and clients as promotional gifts. Stress balls are the third most popular promotional gift in the UK. citation needed date October 2010 Stress toys are a staple of cubicle s where repetitive stress injury repetitive stress injuries such as carpal tunnel syndrome are common. Because of the many shapes now available, stress balls are generically known as stress relievers. Citation needed date August 2007 References reflist Commons category Stress balls DEFAULTSORT Stress Ball Category Ergonomics Category Physical therapy Category Stress Category Balls Category Executive toys ar fr Balle anti stress it Palla anti stress ml ... more details
Orphan date November 2006 Context date October 2009 Stress Migration is a failure mechanism that often occurs in IC metallization aluminum , copper . Voids form as result of vacancy migration driven by the hydrostatic stress gradient. Large voids may lead to open circuit or unacceptable resistance increase that impededs the IC performance. Stress Migration is often referred as Stress Voiding , Stress Induced Voiding or SIV . High temperature processing of copper dual damascene structures leaves the copper with a large tensile stress due to a mismatch in coefficient of thermal expansion of the materials involved. The stress can relax with time through the diffusion of vacancies leading to the formation of voids and ultimately open circuit failures. ref Stress Migration and the Mechanical Properties of Copper, G.B. Alers, et al ref References references Category Semiconductor device fabrication industry stub ... more details
Orphan date February 2009 Incident Stress is a condition caused by acute stress which overwhelms a staff person trained to deal with critical incidents such as within the line of duty for first responders, EMTs, and other similar personnel. If not recognized and treated at onset, incident stress can lead to more serious effects of Post Traumatic Stress Disorder . Signs and symptoms Confusion Lower Attention Span Poor Concentraion Denial Guilt Depression Anger Change in interactions with others Increased or decreased eating Uncharacteristic, excessive humor or silence Unusual behavior People exhibiting signs of Incident Stress require professional help to avoid the more serious condition of Post Traumatic Stress Disorder . See also Critical incident stress management Post Traumatic Stress Disorder References First Aid CPR AED for the Workplace. StayWell Yardley, PA. 2006, p. 63. Category Anxiety disorders medical stub ... more details
Cleanup date June 2008 Traumatic Stress is a commonly used term describing reactive anxiety and depression . It is not a medical term and is not included in the Diagnostic and Statistical Manual of Mental Disorders DSM . What is popularly referred to as Traumatic Stress is covered in DSM IV by Adjustment disorder Adjustment Disorders . This includes subtypes of anxiety , Depression mood depression and disturbance of conduct and combinations of these symptoms. It results from events that are less threatening and distressing than the events that lead to posttraumatic stress disorder . The condition presents in a manner similar to posttraumatic stress disorder , but lacking the same intensity. Category Stress ... more details
A stress field is a region in a body for which the Stress physics stress is defined at every point. Stress fields are widely used in fluid dynamics and materials science . Intuitively, one can picture the stress fields as the Stress physics stress created by adding an extra half plane of atoms to a crystal . The bonds are clearly stretched around the location of the dislocation and this stretching causes the stress field to form. Atomistic bonds farther and farther away from the dislocation center are less and less stretched which is why the stress field dissipates as the distance from the dislocation center increases. Each dislocation within the material has a stress field associated with it. The creation of these stress fields are a result of the material trying to dissipate mechanical energy that is being exerted on the material. By convention these dislocations are labeled as either positive or negative depending on whether the stress field of the dislocation is mostly compressive or tensile. By modeling or dislocations and their stress fields as either a positive compression physical compressive field or negative tension physics tensile field charges we can understand how dislocations interact with each other in the lattice. If two positive fields come in contact with one another they will be repelled by one another. On the other hand if two opposing charges come into contact ... dislocation motion is the primary mechanism behind plastic deformation, increasing the stress required to move dislocations directly increases the yield strength of the material. The theory of stress .... Stress fields can be created by adding different sized atoms to the lattice solute strengthening . If a smaller atom is added to the lattice a tensile stress field is created. The atomistic ... to the lattice a compressive stress field is created. The atomistic bonds are shorter due to the larger radius of the solute atom. The stress fields created by adding solute atoms form the basis of the material ... more details
Unreferenced auto yes date December 2009 Unreferenced date August 2010 Expert subject date August 2010 Stress hormones such as cortisol , growth hormone GH and norepinephrine are released at periods of high stress. The hormone regulating system is known as the endocrine system . Cortisol is believed to affect the metabolism metabolic system and norepinephrine is believed to play a role in ADHD as well as Depression mood depression and hypertension . Stress hormones rise in the body during any neuroendocrine reaction such as surgery and they remain high to as long as 72 hours after which all these hormones return back to their normal level, the last being cortisol. Currently there are medications available which block the release of stress hormones. Stress hormones act by, Mobilizing energy from storage to muscles, Increasing heart rate, blood pressure and breathing rate and Shutting down metabolic processes such as digestion, reproduction, growth and immunity. Constant stress causes continual release of stress hormone which causes A depletion of energy storage High blood pressure Stress induced hypertension Affects on metabolic processes Ulcers digestion Hampers growth Decrease in testosterone levels in males and irregular menstrual cycles in females. Increases likelihood of infectious diseases. DEFAULTSORT Stress Hormone Category Human hormones Med stub de Stresshormone ... more details
Flow stress is defined as the instantaneous value of stress required to continue deforming the material to keep the metal flowing. It is the yield strength of the metal as a function of strain, which can be expressed ref Mikell P. Groover, 2007, Fundamentals of Modern Manufacturing Materials, Processes, and Systems, Third Edition, John Wiley & Sons Inc. ref Yf Ke sup n sup Yf Flow stress, MPa e Strain materials science True strain K Strength Coefficient, MPa n Work hardening Strain hardening exponent Hence, Flow stress can also be defined as the stress required to sustain plastic deformation in solids plastic deformation at a particular strain. The flow stress is a function of plastic strain. The following properties that have an effect on flow stress chemical composition , purity, crystal structure , phase constitution, exit microstructure, grain size , and heat treatment . ref http www.metalpass.com metaldoc paper.aspx?docID 3 Flow Stress Bot generated title ref References reflist Category Metallurgy Category Mechanical engineering engineering stub ... more details
Intro tooshort date January 2010 Wikify date January 2010 Stress management is the amelioration of Stress biological stress and especially chronic stress often for the purpose of improving everyday functioning. Stress produces numerous symptoms which vary according to persons, situations, and severity ... for the study of stress. They measured the physiological responses of animals to external pressures ... cite journal author Selye, H year 1950 title Stress and the general adaptation syndrome journal Br. Med. J. volume 4667 pages 1383 92 pmid 15426759 issue 4667 pmc 2038162 ref Subsequent studies of stress in humans by Richard Rahe and others established the view that stress is caused by distinct, measureable ... of stress they produce leading to the Holmes and Rahe stress scale Holmes and Rahe Stress Scale . Thus, stress was traditionally conceptualized to be a result of external insults beyond the control of those experiencing the stress. More recently, however, it has been argued that external circumstances do not have any intrinsic capacity to produce stress, but instead their effect is mediated by the individual s perceptions, capacities, and understanding. Models of stress management File Models of stress management Transactional model Richard Lazarus and Susan Folkman suggested in 1984 that stress ... when pressure exceeds one s perceived ability to cope . Stress management was developed and premised on the idea that stress is not a direct response to a stressor but rather one s resources and ability to cope mediate the stress response and are amenable to change, thus allowing stress to be controllable. ref Lazarus, R.S., & Folkman, S. 1984 . Stress, Appraisal and Coping. New York Springer. ref In order to develop an effective stress management programme it is first necessary to identify the factors that are central to a person controlling his her stress, and to identify the intervention methods which effectively target these factors. Lazarus and Folkman s interpretation of stress focuses ... more details
Stress shielding refers to the reduction in bone density osteopenia as a result of removal of normal stress from the bone by an implant for instance, the femoral component of a hip replacement hip prosthesis . This is because by Wolff s law , bone in a healthy person or animal will remodel in response to the loads it is placed under. Therefore, if the loading on a bone decreases, the bone will become less dense and weaker because there is no stimulus for continued remodeling that is required to maintain bone mass. External links http cancerweb.ncl.ac.uk cgi bin omd?stress shielding Stress shielding , Online Medical Dictionary. Category Orthopedic surgery Category Skeletal disorders med stub ... more details
Biotic stress is stress biological stress that occurs as a result of damage done to plants by other living organisms, such as bacteria, viruses, fungi, parasites, beneficial and harmful insects, weeds, and cultivated or native plant s. Agriculture It is a major focus of agricultural research, due to the vast economic losses caused by biotic stress to cash crops. The relationship between biotic stress and plant yield affects economic decisions as well as practical development. The impact of biotic injury on crop yield impacts population dynamics , plant stressor coevolution , and ecosystem nutrient cycling. ref Robert K.D. Peterson, Leon G. Higley. Biotic Stress and Yield Loss. 2001. ref Biotic stress also impacts horticultural plant health and natural habitat s ecology. Biological pest control Biological pest control herbivore agents feeding on invasive species results in biotic stress, part of reducing and controlling some noxious weed s in agricultural areas and natural ecosystems. The use of Neochetina eichhorniae mottled water hyacinth weevil Neochetina eichhorniae worldwide on Eichhornia crassipes water hyacinth Eichhornia crassipes is an example. ref http el.erdc.usace.army.mil pmis mergedProjects Biocontrol html neochetina eichhorniae mottled waterhyacinth weevil.htm U.S. Army Engineer Research and Development Center, Waterways Experiment Station Neochetina eichhorniae Mottled Waterhyacinth Weevil . accessed 1.11.2011 ref ref http australianmuseum.net.au image Waterhyacinth Weevil Neochetina eichhorniae Australian Museum Waterhyacinth Weevil, Neochetina eichhorniae . accessed ... biotic stress from root, water, or nutrient competition below the surface, or from shading of sunlight ... stress Biotic component List of beneficial weeds References refs modelling ecosystems Category Stress Category Agroecology Category Habitat management equipment and methods Category Habitat ecology terminology biology stub fr Stress biotique ... more details
Italic title Infobox journal title Stress cover File Stress front cover.jpg thumbnail center discipline Stress biology Stress , neurology abbreviation Stress editor John A. Russell publisher Informa country United Kingdom website http www.informahealthcare.com sts impact 3.205 impact year 2009 frequency Bimonthly history 1996 present ISSN 1025 3890 eISSN 1607 8888 CODEN STREFR OCLC 36276980 Stress is a Peer review peer reviewed medical journal covering interdisciplinary aspects of stress in terms of the mechanisms of stressful stimulation, the physiological and behavioural responses to stress, and their regulation, in both the short and long term adaptive mechanisms, coping strategies and the pathological consequences of stress. This includes research in physiology , neuroscience neurobiology , molecular biology , genetics , immunology , and behavioural studies. Stress is published by Informa and is edited by John A. Russell University of Edinburgh College of Medicine and Veterinary Medicine, UK . Ref Cite web url http informahealthcare.com page EditorialAdvisoryBoard?journalCode sts title Stress Editorial Board accessdate 14 06 2010 ref The journal was established in 1996 and according to the Journal Citation Reports it has a 2009 impact factor of 3.205. The journal is published 6 times a year. ref cite web url http informahealthcare.com loi sts?open 2009 title Stress Online Publications accessdate 09 06 2010 format work ref References Reflist Category Medical journals Category Informa academic journals Category English language journals Category Bimonthly journals Category Publications established in 1996 ... more details
Refimprove date November 2007 Infobox disease Name Stress fracture Image Caption DiseasesDB 7842 ICD10 ... MeshID D015775 This article is about stress fractures in bones. For stress fractures in engineering, see fracture and fatigue material . A stress fracture is one type of incomplete fracture in bones. It is caused by unusual or repeated stress and also heavy continuous weight on the ankle or leg. ref DorlandsDict four 000042557 Stress fracture ref This is in contrast to other types of fractures ... health stress fractures DS00556 title Stress fractures MayoClinic.com accessdate 2007 12 ... sports injury , and most cases are associated with athletics. ref name titleCommon Stress ... title Common Stress Fractures October 15, 2003 American Family Physician accessdate 2007 12 23 work ref Presentation Stress fractures usually have only a few symptoms. A stress fracture could ..., a stress fracture in the leg or foot will cause severe pain at the beginning of the run, moderate ... conditions, a stress fracture is best diagnosed after interview and examination by a physician. Investigations are not necessary to diagnose a stress fracture. X rays usually do not show any evidence of stress fractures, so a CT scan , MRI , or Bone scan 3 phase bone scan may be more effective in unclear cases. Treatment If a stress fracture occurs in a weight bearing bone, healing will be delayed ... of a stress fracture. The amount of recovery time varies greatly depending upon the location ... of rest of twelve to sixteen weeks is not uncommon for more severe stress fractures. After this period ... at significant risk. Activities such as running or sports that place additional stress on the bone ... with a hard plastic boot or air Orthopedic cast cast may also prove beneficial by taking some stress off the stress fracture. An air cast has pre inflated cells that put light pressure on the bone, which ... applied to the bone. If the stress fracture of the leg or foot is severe enough, crutches can ... more details
Cyclic stress in engineering refers to an internal distribution of forces a stress that changes over time in a repetitive fashion. As an example, consider one of the large wheels used to drive an aerial lift such as a ski lift . The Wire rope wire cable wrapped around the wheel exerts a downward force on the wheel and the drive shaft supporting the wheel. Although the shaft, wheel, and cable move the force remains nearly vertical relative to the ground. Thus a point on the surface of the drive shaft will undergo tension when it is pointing towards the ground and compression when it is pointing to the sky. Because the wheel rotates many times during the use of the machine, this cycle of Tensile stress tension and Compressive stress compression is repeated many times &mdash hence the name cyclic stress. Types of cyclic stress Cyclic stress is frequently encountered in rotating machinery where a bending moment is applied to a rotating part. This is called a cyclic bending stress and the aerial lift above is a good example. However, cyclic axial stress es and cyclic torsional stress es also exist. An example of cyclic axial stress would be a bungee cord see bungee jumping , which must support the mass of people as they jump off structures such as bridges. When a person reaches the end ... a large axial stress in the cord. A fraction of the elastic potential energy stored in the cord ... he or she fell. The person then falls on the cord again, inducing stress in the cord. This happens ..., but have a torque that varies significantly over time. Cyclic stress and material failure When ... cyclic stresses into mean and alternating components. Mean stress is the time average of the principal stress. Alternating stress is the difference between the mean and the maximum or the mean and the minimum value the principal stress takes on. Engineers try to design mechanisms whose parts are subjected to a single type bending, axial, or torsional of cyclic stress because this more ... more details
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