AN ANALYTICAL Formulas provide the foundation for test has been used to evaluate the effects technological progress. With only a of structural, thermal, and chemical TREATMENT FOR few symbols, the marvelous language of variables in terms of two material PLASTIC DEFORMATION mathematics can convey vast quantities constants; K, the strength coefficient, of information, with precision, clarity and brevity. Forand n, the strain hardening index.* mulas, however, are valuable tools only when they can be This method, described by one of the leading ausupported by experimental evidence. thorities in the field, is contained in one of our technical Take the expression above, for example. It defines a series (M-5) which is yours for the asking. parabolic relationship which can be used to describe the We certainly do not take credit for the equation — it stress-strain behavior of many materials subjected to represents the efforts of outstanding metallurgical replastic deformation. This equation is not true for all searchers. We do, however, provide the precision instrumaterials and, therefore, the stress-strain relation must ments which are necessary for this type of study. Wherebe found to determine if the formula will apply. Then, ever scientists are probing the secrets of material beif the equation can be shown to be valid for the particular havior, the Instron is often chosen to provide the facts on which theories are built. Instron test instruments are extremely sensitive, yet rugged and versatile machines — truly universal units which function in tension, compression, flexure, and in many other measurements of the nature and behavior of materials. They are equally well suited for problems in basic research or for quality control and similar routine testing. Remember, the unique versatility of the Instron makes it an ideal instrument for work with all types of materials. If you are at all interested in any problem concerned with the investigation of material behavior, we would like to be of help. For example, we offer an extensive selection of scientific articles representing recent and outstanding work in the field of stress-strain analysis. Tell us your particular interest and we will send you available literature on this subject, with0.4 0.6 6 TRUE STRAIN out charge. Experimental Data Confirm the Parabolic Stress-Strain Relationship.
material under study, m a n y interesting possibilities are immediately available for analytical treatment of the stress-strain curve. Using this approach, the tensile
For advanced instrumentation
in
stress-strain behavior- look to
'Formula defining stress-strain relation of some materials under plastic deformation, where: C i s the true stress in lbs. /sq'. in.; 3 represents the true strain, in./in.; K is called the strength coefficient; and n is the strain hardening index.
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