Consider the following four structures:

(i) See Fig. 9.23:

(ii) See Fig. 9.24:

(iii) See Fig. 9.25:

(iv) See Fig. 9.26:

Let F1,F2, and F3 be the corresponding component failure distributions; each of which is assumed to be IFR (increasing failure rate). Let F be the system failure distribution. All components are independent.

(a) For which structures is F necessarily IFR if F1 = F2 = F3? Give reasons.

(b) For which structures is F necessarily IFR if F2 = F3? Give reasons.

(c) For which structures is F necessarily IFR if F1 = F2 = F3? Give reasons.

Transcribed Image Text:

2 3