Roberto Teti

By Alessandra Caggiano and Roberto Teti

Digital simulation approaches applied to railway engineering allow to investigate different railway scenarios via 3D digital twins of real objects, motion simulation, and collision detection to identify the root causes of critical damage and estimate the most likely sources of railway accidents. In this work, a digital simulation approach is applied to a real catastrophic train accident in which a railway carriage carrying a pressure vessel collided with an obstacle that generated a cut in the pressure vessel casing. This cut initiated a liquefied petroleum gas leakage that expanded in the environment and caused the explosion and blaze responsible for human casualties. Traditional railway accident reconstruction procedures identified two potential objects accountable for the cutting of the pressure vessel casing: a wing rail and a track reference stake. Based on digital terrain models and reconstructed models of the railway carriage, 3D digital simulation scenarios were created to detect every possible collision of the pressure vessel with the infrastructure environment and investigate whether the shape of the cut in the pressure vessel wall fits the damage visible on the obstacles and whether the interference between obstacle and pressure vessel wall could generate the chip through an interaction similar to metal cutting.

Part of the book: Modern Railway Engineering

By Alessandra Caggiano, Luigi Nele and Roberto Teti

Composite materials such as fiber-reinforced plastics (FRP) are increasingly employed in the aeronautical industry, where the reduction of aircraft weight is essential to meet environmental and cost requirements related to lower emissions and fuel consumption. Due to structural requirements, aeronautical assembly processes on FRP components are based on the wide use of mechanical joints such as rivets. As the latter require a former hole making process, drilling is extensively applied to FRP composites in the aeronautical industry. The main challenges in FRP composite drilling are related to rapid tool wear and damage generation which affects material integrity and surface quality, with particular reference to delamination damage generation. In this chapter, case studies of drilling of CFRP/CFRP stacks for aeronautical assembly are presented to investigate and discuss the influence of drilling parameters, tool type and geometry on tool wear development, hole quality and surface integrity, and the opportunity to implement advanced sensor monitoring procedures for tool condition monitoring based on the acquisition and processing of thrust force and torque signals.

Part of the book: Characterizations of Some Composite Materials

By Tiziana Segreto, Roberto Teti and Valentina Lopresto

Low-velocity impact damages in composite material laminates, such as matrix cracks, delaminations and fibre breakage, usually develop inside the material and can be difficult to detect. As these flaws downgrade the structural integrity of the composite, the thorough damage evaluation is essential to assess the impact damage criticality. This chapter focuses on the ultrasonic non-destructive inspection of low-velocity impacted composite laminates for damage estimation and assessment. The impact damage generation mechanisms are described and characterised. Ultrasonic testing methods and their defect detection capabilities are illustrated. Recent research studies on ultrasonic non-destructive evaluation of low-velocity impacted composite materials are presented and discussed.

Part of the book: Characterizations of Some Composite Materials