. ، fatigue و cycle…

فهرست عناوین اصلی در این پاورپوینت

فهرست عناوین اصلی در این پاورپوینت

● FATIGUE

نوع زبان: انگلیسی حجم: 0.77 مگا بایت
نوع فایل: اسلاید پاورپوینت تعداد اسلایدها: 20 صفحه
سطح مطلب: نامشخص پسوند فایل: ppt
گروه موضوعی: زمان استخراج مطلب: 2019/06/07 12:49:55

لینک دانلود رایگان لینک دانلود کمکی

اسلایدهای پاورپوینت مرتبط در پایین صفحه

عبارات مهم استفاده شده در این مطلب

عبارات مهم استفاده شده در این مطلب

., stress, fatigue, load, cycle, failure, material, usually, tensile, fracture, crack, n,

توجه: این مطلب در تاریخ 2019/06/07 12:49:55 به صورت خودکار از فضای وب آشکار توسط موتور جستجوی پاورپوینت جمع آوری شده است و در صورت اعلام عدم رضایت تهیه کننده ی آن، طبق قوانین سایت از روی وب گاه حذف خواهد شد. این مطلب از وب سایت زیر استخراج شده است و مسئولیت انتشار آن با منبع اصلی است.

http://home.iitk.ac.in/~anandh/E-book/phase2/Chapter_9e_Fatigue.ppt

در صورتی که محتوای فایل ارائه شده با عنوان مطلب سازگار نبود یا مطلب مذکور خلاف قوانین کشور بود لطفا در بخش دیدگاه (در پایین صفحه) به ما اطلاع دهید تا بعد از بررسی در کوتاه ترین زمان نسبت به حدف با اصلاح آن اقدام نماییم. جهت جستجوی پاورپوینت های بیشتر بر روی اینجا کلیک کنید.

عبارات پرتکرار و مهم در این اسلاید عبارتند از: ., stress, fatigue, load, cycle, failure, material, usually, tensile, fracture, crack, n,

مشاهده محتوای متنیِ این اسلاید ppt

مشاهده محتوای متنیِ این اسلاید ppt

fatigue fatigue of materials cambridge solid state science series s. suresh cambridge university press cambridge ۱۹۹۸ atlas of fatigue curves ed. howard e. boyer american society of metals metals park oh ۱۹۸۶ it is observed that materials subjected to dynamic repetitive fluctuating load stress fail at a stress much lower than that required to cause fracture in a single application of a load.  damage of material due to varying load of magnitude usually less than the yield stress ultimately leading to failure is termed as fatigue of material or fatigue failure . it is estimated that fatigue accounts for ~۹ of all service failures due to mechanical causes. corrosion being the other major cause of failures. the insidious part of the phenomenon of fatigue failure is that it occurs without any obvious warning. usually fatigue failures occur after considerable time of service. the surface which has undergone fatigue fracture appears brittle without gross deformation at fracture in the macroscale . on a macroscopic scale the fracture surface is usually normal to the direction of the principal tensile stress. fatigue failure is usually initiated at a site of stress concentration e.g. a notch in the specimen or an acicular inclusion . the term fatigue is borrowed from human reaction of ‘tiredness’ due to repetitive work fatigue testing is often conducted in bending or torsion mode rather than tension compression mode . bending tests are easy to conduct. in pipes fatigue tests may be done by internal pressurization with a fluid. if the stress have a origin in thermal cycling then the fatigue is called thermal fatigue. salient features overview points note fatigue loading is sometimes used to get a sharp crack in a notched specimen→ called fatigue pre cracking. three factors play an important role in fatigue failure i value of tensile stress maximum ii magnitude of variation in stress iii number of cycles. geometrical specimen geometry and microstructural aspects also play an important role in determining fatigue life and failure . stress concentrators from both these sources have a deleterious effect. residual stress can also play a role. a corrosive environment can have a deleterious interplay with fatigue. factors affecting fatigue failure factors necessary to cause fatigue failure large variation fluctuation in stress sufficiently high maximum tensile stress sufficiently large number of stress cycles if the value of the maximum stress experienced by the material is less than the yield stress should not the material be in a purely elastic state why does failure occur in fatigue loading . funda check let us consider a uniaxial tensile loading. we have already noted that the yield stress y is the macroscopic yield stress and microscopic yielding by slip is initiated at a much lower stress value. in uniaxial loading this slip usually does not lead to any appreciable effects or damage to the material component. in cyclic loading on the other hand due to reversal of slip direction intrusions can be caused on the surface which are like small surface cracks precursors to a full blown crack . once a crack forms from these intrusions due to further cyclic loading local stress amplification takes place. in the presence of the crack the relevant material property to be considered is fracture toughness. click here to know where does yielding start types of stress cycles and parameters characterizing them the pattern of loading experienced by a component may be complicated involving many frequencies and may include vibration fig.۱ below . if the frequency of loading is very high it is referred to as vibration . the ‘essential’ effect of such a loading can be understood by simpler loading patterns like the sinusoidal wave fig.۲ below . tests involving such loading are easy to conduct and the results obtained is easy to interpret. fig.۱ i. completely reversed cycle of stress the simplest loading one can conceive is a sinusoidal wave pattern loading where the stress load oscillates about a mean zero load stress. the stress amplitude a is marked in the figure. ii. purely tensile cycles the stress load oscillation may be sinusoidal but the mean stress load may be such that the stress state during the entire cycle is tensile. needless to say for a given stress amplitude this type of loading is more severe as maximum stress max is min r . various parameters are defined in the equations below. iii. random stress cycles the stress load oscillation may be sinusoidal but the mean stress load may be such that the stress state during the entire cycle is tensile. needless to say for a given stress amplitude this type of loading is more severe as maximum stress max is min r . s n curve engineering fatigue data is usually plotted as a s n curve. here s is the stress and n the number of cycles to failure usually fracture . the x axis is plotted as log n . the stress plotted could be one of the following a max min. each plot is for a constant m r or a. it should be noted that the stress values plotted are nominal values and does not take into account local stress concentrations. most fatigue experiments are performed with m e.g. rotating beam tests . typically the stress value chosen for the stress is low y and hence s n curves deal with fatigue failure at a large number of cycles ۱ ۵ cycles . these are the high cycle fatigue tests. it is to be noted that the nominal stress y but microscopic plasticity occurs which leads to the accumulation of damage. as obvious if the magnitude of stress increases the fatigue life decreases. low cycle fatigue n ۱ ۴ or ۱ ۵ cycles tests are conducted in controlled cycles of elastic plastic strain strain control mode instead …

کلمات کلیدی پرکاربرد در این اسلاید پاورپوینت: ., stress, fatigue, load, cycle, failure, material, usually, tensile, fracture, crack, n,

این فایل پاورپوینت شامل 20 اسلاید و به زبان انگلیسی و حجم آن 0.77 مگا بایت است. نوع قالب فایل ppt بوده که با این لینک قابل دانلود است. این مطلب برگرفته از سایت زیر است و مسئولیت انتشار آن با منبع اصلی می باشد که در تاریخ 2019/06/07 12:49:55 استخراج شده است.

http://home.iitk.ac.in/~anandh/E-book/phase2/Chapter_9e_Fatigue.ppt

  • جهت آموزش های پاورپوینت بر روی اینجا کلیک کنید.
  • جهت دانلود رایگان قالب های حرفه ای پاورپوینت بر روی اینجا کلیک کنید.

رفتن به مشاهده اسلاید در بالای صفحه


پاسخی بگذارید

نشانی ایمیل شما منتشر نخواهد شد. بخش‌های موردنیاز علامت‌گذاری شده‌اند *