16-1

Reliability growth data from a spacecraft are given in Table 16.14. These data are based on successive design analysis only, because no test or use data were available at the time the predictions were made. The increase in the predicted reliability reflected the increase in the detailed knowledge about the design, its components, their failure rates, and the mission duration. Do the following:

1. Find the math model for the reliability growth curve, using the Gompertz model.

2. Find the reliability that may be attained at the end of January of the following year, i.e., two months after November when the last reliability prediction was made, or in the seventh month ( T _a = 7).

3. Find the upper reliability limit that may be achieved if the current effort continues.

Observe that for T _a = 0 the Gompertz model gives R( T _a = 0) when growth is about to start, in this case the month of June 19XX. The first month's reliability growth is obtained by substituting T _a = 1, the second month's by substituting T _a = 2, etc.

16-2

Given the reliability growth data of Table 16.15, do the following:

1. Find the parameters of the Gompertz reliability growth curve.

2. Write the Gompertz reliability growth equation.

3. Plot the Gompertz curve and the data points on linear-linear scale.

4. Discuss the results of Case 3 comparatively and describe the shape of the reliability growth curve and the raw data.

16-3

Given the...