Nptel, an elearning initiative by the 7 indian institutes of technology and the indian institute of science with the support of the mhrd, govt. Kinematics of machines nptel online videos, courses. Theories of failure free download as powerpoint presentation. The national programme on technology enhanced learning nptel, a project funded by the ministry of human resource development mhrd was first conceived in 1999 to pave the way for introducing multimedia and web technology to enhance learning of basic science and engineering concepts. Initiation of inelastic plastic behavior in the material. An historical view of mechanical failure prevention technology. When a structural element is subjected to a system of complex stress system, it is important to predict the mode of failure so. Static failure theories predicting failure in members subjected to uniaxial stress is both simple and straightforward. In simple terms, the formula says that failure occurs when the principal stress reaches the yield stress. Requirement of tof theories of failure are used to determine the safe dimension of a component when it is subjected to combined stresses due to various loads. Fatigue one of the most common failure mode is without doubt fatigue. This type of failure is the characteristic of brittle materials.
A number of theories have been proposed for the brittle and ductile materials. Nptel video lectures, iit video lectures online, nptel youtube lectures, free video lectures, nptel online courses, youtube iit videos nptel courses. Lecture 2 microcracking of concrete stressstrain behavior in multiaxial loading. Dixit professor mechanical engineering iit kanpur, kanpur, india, 208016. Ravindra gettu, department of civil engineering, iit madras. Identify the failures modes the way the product failed 2. Open publication revision history revision date description a 11 p th p nov 2006 document assembled from other files b6 14 p th p feb 2009 3 p rd jan 2007update based on test results. How to download all of the lectures for a course in nptel. Biological systems make use of feedback in an extraordinary number of ways, on scales ranging from molecules to cells to organisms to ecosystems. Generally, in the elastic range, materials are considered as either ductile like steel, copper, aluminum, etc or. A machine frame made of steel having known sy and ssy is loaded in a test fixture.
Theories of failure play a key role in establishing the relationship between stresses induced under. Srinivasan chandrasekaran, department of ocean engineering, iit madras. Tech library kafb,nm failure criteria for filamentary composites by christos c. One example is the regulation of glucose in the bloodstream through the production of insulin and glucagon by the pancreas. Download notes on theory of computation, this ebook has 242 pages included. Towards a theory of project failure article pdf available in international journal of management concepts and philosophy 22. Two failure properties suffice to predict the general failure conditions under all states of stress. Thus, the function of the theories of elastic failure is to predict from the behavior of materials in a simple tensile test when elastic failure will occur under any conditions of applied stress. When dealing with the design of structures or components the physical properties of the constituent materials are usually found from the results of laboratory experiments which have only subjected the materials to the simplest stress conditions. Nptel material is available for free on nptel website. Different modes of crack growth for example fatigue, stress corrosion cracking and hydrogen embrittlement etc. An historical view of mechanical failure prevention technology henry c. Pusey, shock and vibration information analysis center, winchester, virginia paul l. The principal stresses at two critical points on the surface are known.
These video classes have been developed based on the latest gate syllabus and will be useful for mechanical engineering. Dynamic theory of failure 07 theory of failures youtube. A single stress component z can exist on the zaxis and the state of stress is still called 2d and the following equations apply. A complete and comprehensive theory of failure is developed for homogeneous and isotropic materials. Failure analysis in mechanical components of commercial.
Failure theories study notes for mechanical engineering. Nptel mathematics video lecture online study material. Lecture 3 failure theories and concrete plasticity please sign up for the course before starting the lesson. Failure analysis can help isolate the causes of catastrophic failures and identify a root cause or causes, and, as a result, recommendations to prevent future problems can be made. The knowledge of this subject is very essential for an engineer in.
Optimize a design comparing different failure theories. Howard enterprises, newmarket, new hampshire in april 1967, 42 engineers and scientists concerned with the troublesome and costly problems of mechanical failures met at. Theory of machines is an applied science of the relationships between geometry and relative motion of the parts of the machine, and concerns to the forces which act on those parts. Theories of failure are those theories which help us to determine the safe dimensions of. Networks, signals and systems lecture series on networks,signals and systems by prof. Distributed under creative commons attributionsharealike cc bysa. So, you want to download all of the video lectures for a course in nptel. The failure effects on higher levels in the structure, from subassemblies to the whole system.
Tresca failure criterion maximum shearstress theory the formula presented here applies for planestress conditions only. Identify the failure mechanism the physical phenomena involved in the failure 6. This short course intends to provide a practical understanding of fail. Fatigue is the progressive, localized, and permanent structural change that occurs in a material subjected to repeated or fluctuating strains at nominal stresses that have maximum values less than and often. Identify the failure site where in the product failure occurred 3. We are dedicated to helping clients from around the world using stateoftheart technology, software, and expertise spanning decades of experience to evaluate. Compute the test load at which the frame will experience initial yielding according to the a maximumnormalstress theory. The objective is to establish recommendations to substantially reduce the frequency and the consequences of the failures. The failure rates of each mode, or of each component combined with failure mode frequency. But, predicating the failure stresses for members subjected to biaxial or triaxial stresses is much more complicated. Chamis lewis research center cleveland, ohio national aeronaut ics and space admlnistrati on for sal. Case studies in engineering failure analysis will be discontinued as of end of 2017. Thus, the function of the theories of elastic failure is to predict from the behavior of materials in a. Theories of failure memorial university of newfoundland.
Similar to the maximum shear stress theory but also accounts for the uneven material properties of brittle material. Construction of yield surfaces for failure theories. Significant infrastructure has been set up earlier for production of. Lecture 3 failure theories and concrete plasticity. Theories of failure maximum shear stress theory to use this theory for either two or threedimensional static stress in homogeneous, isotopic, ductile materials, first compute the three principal stresses 1, 2, 3 and the maximum shear stress as 12 max 2 max min 2 pp then compare the maximum shear stress to the failure criterion. Fracture of the material of which the member is made. Failure analysis in component design failure prevention perspective primary responsibility of a designer. Theory of computation automata notes pdf ppt download.
During the latter part of the 19th century and continuing up to the present, a number of basic failure theories were proposed and tested on a few materials. Summary of structural material failure theories having completed a stress analysis of a part you must decide if it predicts a material failure. There are several ways in which problems involving this combination of stresses may be solved, but the following are important from the subject point of view. The full range of materials types are covered from very ductile metals to extremely brittle glasses and minerals. If you are not able to download lectures due to bandwidth constraints, you can obtain the courses in dvds by paying a nominal fee to cover the cost of storage media and distribution. The most usual test is the simple tensile test in which the value of the stress at yield or at fracture whichever occurs. Strength of materials and failure theories 2010 state of stress this is a 2d state of stress only the independent stress components are named. Such faults are commonly caused by poor connections. Related to the parametric failure is the failure of the component to work correctly over the intended range of environments circuits may malfunction at low or high temperature, or under conditions of vibration. The failure analysis is a procedure to determine the physical cause of the failure of an element, component or industrial equipment.
142 1505 1344 1627 115 127 530 946 39 539 206 120 1242 1223 123 1643 1412 1502 164 381 178 296 467 1218 511 271 1449 327 426 989 1212 1026 684 1134 1438 1498