Structures (or Mechanisms) and Load Analysis

Abstract

After mechanical products are designed, we can find the structure and their mechanism. In operation the mechanical/civil systems will work interactively and is subjected to (random) loads. This chapter will discuss how to analyze the loading characteristics of that is the root cause and dominant factor of the product failure. Product has their own particular structural loads in field. Mechanical engineer is designed to have the proper shape and material of mechanical structure with enough strength and stiffness. It therefore can withstand the effects—deformation, vibration, etc.—of system loads in its lifetime. If not, a typical pattern of repeated load or overloading may cause a small portion of structural failures suddenly in its lifetime. Rare possibility such as product failure should be assessed through parametric Accelerated Life Testing in the design phase whether final design of product is properly designed. As first step, there is a modeling of the dynamics systems that can be implemented by traditional method like Newtonian or bond-graph. The time response of mechanical system for (random) dynamic loads represents from its modeling. If simplified and counted as a sinusoidal input for mechanical (or civil) structure, the rain-flow counting method and miner’s rule can enable engineer to assess the system damages—fracture and vibration—for dynamic loading. However, because there are a lot of assumptions for this analytic methodology, it is exact but complex to reproduce the product recalls due to the design failures. So we should develop the final solutions—experimental method like parametric ALT that will be discussed in Chaps. 8 and 9. Load analysis also will be helpful to figure out why the failure of problematic parts in mechanical engineering is revealed.