T H O L I A N S

[Deputy Commander Turner]

Commodores Log - NCC-1742 - stardate 090701.1

I have entered an uncharted region of space to answer a distress call from
our sister ship, the USS Decadent, . . . Nearing the location, . . my engines
are begining to lose power and my sensors detect a nearby dimensional
fracture in space that seems to be the cause of the energy drain.

The Decadent appears on the monitor, adrift, and with a strange green
glow surrounding the hull. Strangely, sensors show no indication that the
vessel is there. There are no lifeforms detected, nor are communications
established with the ship.


Perhaps I will assemble a landing party to beam over and investigate.
Admiral - we will take environmental suits.

[Deputy Commander Turner]

We have managed to retrieve data concerning why the Decadent was out this far. They appear to have come on a scientific mission to perform some type of Notch dwell fatigue testing on the energy array. Transcipts as followws:

The material selected for this program was LSHR, a third-generation PM superalloy developed by UFP, strengthened by about 60-percent gamma prime phase. Six commercially viable heat treatments, presented in the table, were evaluated in this program, producing a variety of microstructures. Each heat-treatment option was designed to produce a different mix of tensile, creep, and crack-growth properties.

The notch dwell fatigue tests were run using a peak, net section stress of 793 MPa that was applied for 90 sec in each cycle. The selection of stress was aggressive but reasonable for a disk rim application. Because these tests were quite lengthy, the initial screening matrix called for testing up to six specimens from each heat-treatment lot to failure, or a 10,000-cycle runout condition, approximating the life requirement for turbine disks.

Notch dwell fatigue testing of the first 12 specimens, 2 from each heat treatment, produced very interesting results. Three of twelve failed in less than 1000 cycles, whereas all others reached the 10,000-cycle runout condition. Because of these results, the remaining 24 tests were run to 2000 cycles to accelerate data acquisition and enhance statistics on failure after less than 1000 cycles. The results of all 36 tests showed that the failures were bimodal, with 7 of 36 specimens failing in less than 1000 cycles and the remaining specimens reaching the desired runout lives. Preliminary examination of the failed specimens (see the photomicrograph) did not reveal anything unusual on the fracture surface; that is, no large pores or inclusions. In the bar chart, the fraction of specimens that failed is plotted as a function of heat treatment. As seen in this plot, all the low-life failures were with the J1 and H1 heat treatments. Although the J1 and H1 heat treatments are different in certain respects, they both produce microstructures with the best creep resistance and, therefore, are the most resistant to stress relaxation. This suggests that higher stress levels maintained during the dwell for J1 and H1 may have led to premature failure.

[Deputy Commander Turner]

2408.0708

I have assembled a landing party in environmental suits
and transported aboard the USS Decadent

[Deputy Commander Turner]

2408.0710 S 4212.1

We have completed our search and scans aboard the Decadent.

It appears that the crew have perished in combat , either by attacking themselves
or fighting a band of mauroders. There are no life signs. A study of the sickbay indicates no entry from the ships medical officer. If it was a medical condition or infection, it must have spread rapidly.

[Deputy Commander Turner]

2408.0710 S 4212.2

I have cancelled the request for a security team and am preparing to beam back to the Nevada. I have promoted Commander Sims to XO, and in my absence, he is in command of the Nevada.