Performance and cost trade-offs are a constant in engineering design. Optimizing a design to balance these competing forces can be challenging to quantify and we often have to resort to experience or intuition. One of the traditional cost drivers is specifying tolerances. Part dimensions are naturally random variables since each part manufactured will not be …
MEboost allows for easy analysis of a tolerance stack. In this article we’ll show how to perform worst case, root sum squared (RSS), and Monte Carlo tolerance analysis in Excel using MEboost. If you want more background information on the three methods, check out the tolerance analysis article. PART I Basic Concepts Before we start …
Affinity laws are used to relate the performance of a pump or fan from a known operating condition to a new, unknown condition. The affinity laws can be calculated at a single point or charts of flow rate, head, and power can be plotted against changes in impeller speed or diameter. Changes to a pump’s …
The Bernoulli equation is a useful way of approximating the state at a point in a streamline given the state at another point. Sometimes we have a situation where it’s easy to measure or observe the state of a point in a fluid system, but we want to know the state of the system at …
A vibration transmissibility plot is a useful way of seeing the response of a harmonic oscillator. In this article we’ll go over the basics of undamped and damped vibration as well as understanding what a vibration transmissibility plot means. In the context of this article, we will be considering spring – mass and spring – …
A part under alternating stress can result in failure from fatigue at stress levels below the yield strength of a material. We can use the stress life approach to fatigue analysis to develop designs that guard against fatigue failure. Machine elements that are subjected to cyclic loads that change over time with the same amplitude …
When spectral loading is present, Miner’s rule is often used as a way to determine the amount of cumulative damage that has occurred. In this article we will discuss the use of Miner’s rule and how it is used to determine either damage that has already occurred, or to provide an estimate of fatigue life. …
The K-Factor method is a versatile way of calculating sheet metal flat blank dimensions. MEboost employs the K-factor method to calculate flat blanks in two directions. Consider the flat blank below. We have already designed the formed part and need to know the overall dimensions as well as the location of the bend lines. Calculating …
Mohr’s circle is a handy tool for determining principal stresses in a body under plane stress. We will dive into the basics of Mohr’s circle and how it is easily created using MEboost. Mohr’s Circle Basics When conducting critical plane analysis, Mohr’s circle can be used to determine the critical plane where maximum damage occurs. …
Traditional engineering design employs the concept of a safety factor to prevent failure. In this article we are going to discuss, with a simple example, how probabilistic design can be used as an alternative to safety factors. Background on Safety Factors In engineering design, uncertainties in material strength, material dimensions, and loading is often accounted …