sf(x) Engineering, Inc.

Given a hole through an aluminum plate in tension.   Hand calculation results show a maximum stress of 30,198 psi vs.software analysis at 29,625 psi or a 1.9% difference.  Only a quarter of the plate is shown in the animation to reduce the model size.  NEi Nastran is excellent software.  More information on NEi can be found at; http://www.nenastran.com/.

Link to hand calculation

Link to NEi Nastran animation file

The Beechcraft King Air (http://www.kingair.org/) is a reliable aircraft, powered by two extremely reliable engines (PT6's).  In-flight shut downs (IFSD) are rare, with a documented failure rate, ranging from 0.01 to 0.003 per 1000 hrs of operation.  Given two engines per aircraft and a one hour flight, what is the failure probability of an in-flight shutdown of both engines? less than 1 in 20 billion hrs - very rare!

Link to pdf hand calculation

The Weibull function can be used in many applications.  Given a five cycle design application and test data (cycles to failure), find the probability that the design meets the required number of cycles?

Link to example

-  under development -