Engineering topics

Manson, S. S.

Publications and source records attributed to Manson, S. S..

At least 37 records · Page 2

NASA NTRS1979

Inversion of the strain-life and strain-stress relationships for use in metal fatigue analysis

The paper presents closed-form solutions (collocation method and spline-function method) for the constants of the cyclic fatigue life equation so that they can be easily incorporated into cumulative damage analysis. The collocation method involves conformity with the experimental curve at specific life values. The spline-function method is such that the basic life relation is expressed as a two-part function, one applicable at strains above the transition strain (strain at intersection of elastic and plastic lines), the other below. An illustrative example is treated by both methods. It is shown that while the collocation representation has the advantage of simplicity of form, the spline-function representation can be made more accurate over a wider life range, and is simpler to use.

Manson, S. S.↗

NASA NTRS1979

Predictive analysis of metal fatigue in the high cyclic life range

This report summarizes various aspects of predictive approaches in high cycle fatigue, hcf. The distinction between hcf and low cycle fatigue, lcf, is discussed in relation to the transition life and strainrange, and curves are presented to establish regions wherein each range predominates depending on the properties of any material of interest. The role of loading order on hcf in cumulative damage analysis is also discussed, together with mean stress effects and their relaxation. Also briefly discussed are high temperature fatigue and ultra-high cycle fatigue.

Manson, S. S.↗

NASA NTRS1978

The development and application of strainrange partitioning as a tool in the treatment of high temperature metal fatigue

The effects of frequency, stress and strain hold periods, stress and strain ramping, creep-fatigue interspersion, and thermomechanical cycling were studied. Of special interest was the establishment of a set of universalized life relations which were normalized by the ductility of the material. These relations together with a set of rules that were devised for treating multiaxiality by the method, were, for example, useful in predicting torsion behavior, and in particular in establishing a new relationship between torsion and tension that had previously not been considered. They also were useful in the development of a framework for treatment of environmental effects.

Manson, S. S.↗

NASA NTRS1978

Interpolation and extrapolation of creep rupture data by the minimum commitment method. II - Oblique translation

An outline is presented of a new procedure, termed the oblique translation method, which emerged in the development of the focal point convergence method. Approaches for implementing the oblique translation method are discussed. It is shown that the new method is essentially a minimum commitment method when manually-graphically implemented, in the sense that the form of the functions involved are not forced into particular analytical forms. The individual constants and functions are independently determined. The minimum commitment concept is extended to the analysis of creep rupture data wherein each isothermal is to be generated by an oblique translation of the 'master curve' when plotted. Attention is given to a manual-graphical analysis, the preassessment of data, and an analysis by computer code.

Manson, S. S.↗

NASA NTRS1978

Interpolation and extrapolation of creep rupture data by the minimum commitment method. I - Focal-point convergence

The minimum commitment method has been applied to the analysis of creep-rupture data. The method is based on a parameter representing the focal point of convergence of all isothermals when extended to the long or short times necessary for such convergence to occur. The technique may be applied by manual-graphic analysis on computer code. It is illustrated for the nickel-base alloy Astroloy.

Manson, S. S.↗

NASA NTRS1978

Interpolation and extrapolation of creep rupture data by the minimum commitment method. III - Analysis of multiheats

An outline is presented of approaches for treating multiheats on the basis of the focal point convergence method. The method has been employed in the case of two highly characterized multiheats, including a 304 stainless steel studied in Japan and a low alloy carbon steel studied in England. The method makes use of the same functional form for all materials. Only the constants are varied for each multiheat. Completely computerized procedures are employed for the determination of the constants. Once the basic analysis has been performed, the representation of various members in the same system is achieved by adding linear expressions of log stress, changing only two constants in the equations to represent a selected heat.

Manson, S. S.↗

NASA NTRS1978

Interpolation and Extrapolation of Creep Rupture Data by the Minimum Commitment Method. Part 3: Analysis of Multiheats

The Minimum Commitment Method was applied to two sets of data for which multiple heat information was available. For one alloy, a 304 stainless steel studied in Japan, data on nine well characterized heats were used, while for a proprietary low alloy carbon steel studied in the United Kingdom data were available on seven heats - in many cases to very long rupture times. For this preliminary study no instability factors were used. It was discovered that heat-to-heat variations would be accounted for by introducing heat identifiers in the form A + B log sigma where sigma is the stress and the constants A and B depend only on the heat. With these identifiers all the data could be collapsed onto a single master curve, even though there was considerable scatter among heats. Using these identifiers together with the average behavior of all heats made possible the determination of an accurate constitutive equation for each individual heat. Two basic approaches are discussed for applying the results of the analysis.

Manson, S. S.↗

NASA NTRS1978

Interpolation and extrapolation of creep rupture data by the Minimum Commitment Method. I - Focal-point convergence. II - Oblique translation. III - Analysis of multiheats

The framework in which minimum-commitment analyses of creep-rupture data can be implemented is outlined. The approach is termed the focal point convergence method (FPCM) because the basic parameter A, also known as stability factor, is geometrically the (imaginary) focal point of convergence of all isothermals when extended to the very long or very short times necessary for such convergence to occur. The method can be implemented either by manual-graphical analysis or by computer code. The method is illustrated in detail for the nickel-base alloy Astroloy, as well as for steels, other nickel-base alloys, and aluminum alloys. The minimum-commitment concept is extended to the analysis of creep-rupture data where each isothermal is generated by an oblique translation of the 'master curve' when plotted on log rupture time and log stress axes. The oblique translation method uses the same types of functions in the FPCM. Approaches for treating multiheats on the basis of the FPCM are discussed in detail.

Manson, S. S.↗

NASA NTRS1977

Treatment of low strains and long hold times in high temperature metal fatigue by strainrange partitioning

A procedure for treating creep-fatigue for low strainranges and long hold times is outlined. A semi-experimental approach, wherein several cycles of the imposed loading is actually applied to a specimen in order to determine the stable hysteresis loop, can be very useful in the analysis. Because such tests require only a small fraction of the total failure time, they are not inherently prohibitive if experimental equipment is available. The need for accurate constitutive equations is bypassed because the material itself acts to translate the imposed loading into the responsive hysteresis loops. When strainrange partitioning has been applied in such cases very good results have been obtained.

Manson, S. S.↗

NASA NTRS1975

Life prediction of thermal-mechanical fatigue using strainrange partitioning

This paper describes the applicability of the method of Strainrange Partitioning to the life prediction of thermal-mechanical strain-cycling fatigue. An in-phase test on 316 stainless steel is analyzed as an illustrative example. The observed life is in excellent agreement with the life predicted by the method using the recently proposed Step-Stress Method of experimental partitioning, the Interaction Damage Rule, and the life relationships determined at an isothermal temperature of 705 C. Implications of the present study are discussed relative to the general thermal fatigue problem.

Halford, G. R.↗

NASA NTRS1975

Separation of the strain components for use in Strainrange Partitioning

Two methods are presented for separating the inelastic strain components of a complex hysteresis loop so that Strainrange Partitioning formulas can be applied to accurately determine cyclic life at elevated temperatures. These methods are required only if lower bounds established by Strainrange Partitioning concepts have been deemed inadequate in the establishment of expected lifetime. In one method rapid loading and unloading is applied in the tensile and compressive half to isolate the plastic strain. In the second method the 'creep' is measured at a discrete number of points along the hysteresis loop by combining load-control tests into the general pattern of strain cycling under arbitrary temperature. Both methods are shown to give good results.

Manson, S. S.↗

NASA NTRS1975

Separation of the strain components for use in strainrange partitioning

Two methods are presented for separating the inelastic strain components of a complex hysteresis loop so that strainrange partitioning formulas can be applied to accurately determine cyclic life at elevated temperatures. These methods are required only if lower bounds established by strainrange partitioning concepts have been deemed inadequate in the establishment of expected lifetime. In one method, rapid loading and unloading is applied in the tensile and compressive half to isolate the plastic strain. In the second method, the creep is measured at a discrete number of points along the hysteresis loop by combining load-control tests into the general pattern of strain cycling under arbitrary temperature. Both methods are shown to give good results.

Manson, S. S.↗

NASA NTRS1975

Life prediction of thermal-mechanical fatigue using strain-range partitioning

The applicability is described of the method of Strainrange Partitioning to the life prediction of thermal-mechanical strain-cycling fatigue. An in-phase test on 316 stainless steel is analyzed as an illustrative example. The observed life is in excellent agreement with the life predicted by the method using the recently proposed Step-Stress Method of experimental partitioning, the Interation Damage Rule, and the life relationships determined at an isothermal temperature of 705 C. Implications of the study are discussed relative to the general thermal fatigue problem.

Halford, G. R.↗

NASA NTRS1974

An overview of high temperature metal fatigue: Aspects covered by the 1973 International Conference on Creep and Fatigue

A summary of papers is presented which covers the following broad aspects of high temperature metal fatigue: (1) materials development and characterization; (2) environmental factors, including air, vacuum, helium, iodine, sodium, and radiation environments; (3) general fatigue life relationships; (4) crack growth laws; (5) design code activities; and (6) design and service experience. Illustrative tables accompany the summary.

Manson, S. S.↗

NASA NTRS1973

Creep-fatigue analysis by Strainrange Partitioning

Strainrange Partitioning provides unifying framework for characterizing high-temperature, low-cycle, creep-fatigue properties of metals and alloys. Method offers distinct advantage to designers of immediately providing reliable upper and lower bounds on cyclic life for any type of inelastic strain cycle that may be encountered in service.

Manson, S. S.↗

NASA NTRS1972

Temperature effects on the strainrange partitioning approach for creep-fatigue analysis.

Examination is made of the influence of temperature on the strain-range partitioning approach to creep-fatigue. Results for 2.5Cr-1Mo steel and Type 316 stainless steel show the four partitioned strain range-life relationships to be temperature insensitive to within a factor of two on cyclic life. Monotonic creep and tensile ductilities were also found to be temperature insensitive to within a factor of two. The approach provides bounds on cyclic life that can be readily established for any type of inelastic strain cycle.

Halford, G. R.↗

NASA NTRS1972

The challenge to unify treatment of high-temperature fatigue - A partisan proposal based on strainrange partitioning.

The strainrange partitioning concept divides the imposed strain into four basic ranges involving time-dependent and time-independent components. It is shown that some of the results presented at the Symposium can be better correlated on the basis of this concept than by alternative methods. It is also suggested that methods of data generation and analysis can be helpfully guided by this approach. Potential applicability of the concept to the treatment of frequency and hold-time effects, environmental influence, crack initiation and growth, thermal fatigue, and code specifications are then briefly considered. A required experimental program is outlined.

Manson, S. S.↗

NASA NTRS1972

Temperature effects on the strainrange partitioning approach for creep-fatigue analysis

Examination is made of the influence of temperature on the strainrange partitioning approach to creep-fatigue. Results for Cr-Mo steel and Type 316 stainless steel show the four partitioned strainrange-life relationships to be temperature insensitive to within a factor of two on cyclic life. Monotonic creep and tensile ductilities were also found to be temperature insensitive to within a factor of two. The approach provides bounds on cyclic life that can be readily established for any type of inelastic strain cycle. Continuous strain cycling results obtained over a broad range of high temperatures and frequencies are in excellent agreement with bounds provided by the approach. The observed transition from one bound to the other is also in good agreement with the approach.

Halford, G. R.↗