Stress-rupture data

Stress-rupture data are often presented in a Larson-Miller eurve, whieh indieates the performanee of an alloy in a eomplete and eompaet graphieal style. While widely used to deseribe an alloy s stress-rupture eharaeteristies over a wide temperature, life, and stress range, it is also useful in eomparing the elevated temperature eapabilities of many alloys. The Larson-Miller parameter is... 

Fig. 2-36 Stress-rupture data for rigid 2 in. diameter PVC pipe as a function of temperature.

Manson, S. S., et al., A linear Time-Temperature Relation of Creep Stress Rupture Data, NACA, TN 2890,1953. 

ISO/DIS 9080, Thermoplastics pipes for the transport of fluids - Methods of extrapolation of hydrostatic stress rupture data to determine the long-term hydrostatic strength of thermoplastics pipe materials, 1992. 

Where to, A17, t) are constants for a given fibre, applied stress and Tis the absolute temperature. Zhurkov achieved an excellent correlation between AU calculated from such stress-rupture data and Al/ , the activation energy for thermal degradation for a wide range of fibres. It was also possible to identify the free radicals and degradation products formed... 

Fig. 1. Schematic stress rupture data, illustrating the effect of temperature on time to failure...

Fig. 6.94 Stress rupture data of Fig. 6.79 replotted including the high stress flexure data for ARCO alumina [74]. With kind permission of John Wiley and Sons...

The resulting stress rupture data will be used to examir ie the applicability of a generalized fatigue-life (slow crack growth) model. If necessary, model refinements will be implemented to account for both crack blur tlng and creep damage effects. Insights obtained from the characterization studies will be crucial for this modification process. 

Table 3.8. Extrapolation factors (according to DIN 16887) which determine the time limits for which extrapolation of stress-rupture data are allowed as a function of the difference between maximum test temperature and service temperature AT...

Sufficient data for HDPE geomembrane materials are not usually available from pipe pressure tests which would enable a direct extrapolation of the stress-rupture curve at 23 °C or 40 °C according to the instmctions of ISO 9080 for small stresses and longer times. The emphasis is on the brittle branch of the stress-rupture curve which results from brittle failures and determines the failure behaviour at small stresses and extremely long service lifetimes. However, one can use the experience accumulated with HDPE materials over many decades (Schulte 1997 Krishnaswamy 2005) and fall back on the extrapolation factors of DIN 16887 or ISO 9080 which were checked by measured stress-rupture data of polyethylene pipes. These factors Ke give the time limits of a permissible extrapolation of the stress-rupture curves in the following sense. Let us assume that hoop stress versus times-to-failure data are measured at several higher test tempera-... 

Voorhees, Sliepcevich, and Freeman (204) have presented a procedure for calculating the time of rupture from creep and stress-rupture data normally available to a designer. Prior to the work of Voorhees the design of thick-walled vessels at high pressures and elevated temperatures was usually based upon the maximum principal stress and an allowable stress determined from creep and stress-rupture test data. This is the current method recommended by the ASME code (11) for vessels operating at pressures up to 3000 psi. 

In the case of alloys for hi - aperature service having high cr p str glJ+ the d ign should bas on stress-rupture data ratoer than creep rate. The recommended stress for dh a is 0.8 the st ss for rupture in the... 

Two trends make this data non-ideally behaved 1) dramatically increased scatter at lower applied stresses, and 2) pronounced nonlinear behavior in the stress rupture data as the applied stresses became lower (the strength data shifted to the right which signified that the lives became longer than would have been predicted if the standard power law was applicable). An ideally behaved data set would show a... 

The stress rupture data is analyzed by statistical regression to generate a hoop stress versus time equation. This equation is extrapolated mathematically one decade of time to 100,000hr (approximately 11.4yr) to obtain a 100,000-hr design stress. 

FIGURE 13.3 Stress rupture data plotted as best-fit straight line and extrapolated to determine long-term hydrostatic strength. (Derived from A.G.A Plastic pipe Manual for Gas Service)... 

Internal stress rupture data on its DHDA 2077 Tan resin... 

The company was required to foUow the PPI procedure in developing the necessary stress rupture data, but no requirement existed for those data to be submitted to the PPI or for the PPI to assign a listing before the tested material could be marketed. 

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