Crashworthiness through smart use of high failure strain steel

摘要

The crashworthiness of a structure can have a large effect on the area based risk in case of collisions. Typical examples are chemical tankers sailing the European inland waterways and offshore structures at our shores. Therefore, the assessment of crashworthiness is nowadays often included in the design process of such structures. But what if the design needs to be improved to meet the crashworthiness requirements? This paper describes a method to improve the crashworthiness of a ship structure by a smart use of high failure strain steel. It shows how the use of such material can be effective. High failure strain steels are normally more expensive than normal shipbuilding steels, so an optimization of the use of these materials is required. Therefore, a methodology is developed to determine the critical structural part(s) that would benefit most from the application of such steels. An example case of an inland waterway chemical tanker is given to illustrate the procedure. In this example, the crashworthiness of the design is determined through explicit FEM calculations. An elasto-plastic material model is used and material failure is included using a through thickness failure criterion with element deletion. Since this criterion was developed for mild steel it had to be adapted and validated for high failure strain steel using lab tests.