PSI - Issue 2_A

Goran Vukelic et al. / Procedia Structural Integrity 2 (2016) 2944–2950 Author name / Structural Integrity Procedia 00 (2016) 000 – 000

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b)

c)

Fig. 2. Fractured coil spring with a detail of fractured surface.

Fracture surface of the spring is also covered in rust, Fig 2 (c). Part of the surface where crack initiated is covered in thicker, darker layer of rust. This is due to the fact that this was a portion of the fracture surface which formed gradually and was exposed to corrosion for longer period of time before the final failure. Secondary crack area that represents the accelerated stage of fracture is covered in lighter layer of rust. Closer look at the fracture surface reveals corrosion pit at the place where the protective paint layer was damaged. Fracture originated from this point and radiating ridges emanating from this point suggest fatigue failure caused by cyclic loading from the vehicle. At the opposite side of the crack origin (lower edge of the wire), fast fracture area can be observed corresponding to the final stage of failure.

2.2. Spring material

Chemical composition of spring material was determined using glow discharge spectrometer (GDS) LECO GDS500A, Tab. 1.