Failure of a Trunnion Axle on a Hard Suspension Multi-axle Trailer
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CASE HISTORY—PEER-REVIEWED
Failure of a Trunnion Axle on a Hard Suspension Multi-axle Trailer Joseph A. Lemberg . Brett D. Ellis . Eric P. Guyer
Submitted: 19 December 2016 / Published online: 6 February 2017 ASM International 2017
Abstract The failure analysis of a trunnion axle on a hard suspension multi-axle trailer is presented. All reported failures have occurred in an unloaded state very shortly after being put into service at or near the top of the trunnion axle in close proximity to a welded round plate. Analyses indicated a pre-existing flaw in the heat-affected zone near the weld. The unloaded state of the trailer, which may have exacerbated the dynamic loading, coupled with the limited damping provided by the hard suspension was likely the driving force for this failure.
The trailer was reportedly traveling empty to its first load pickup when the failure occurred. Similar failures have been reported for this type of trailer. These failures were not limited to the road-side front wing jeeps. All reported failures occurred at or near the top of the trunnion axle in close proximity to the weld attaching the trunnion axle to the suspension assembly (Fig. 2), while trailers were towed in an unloaded configuration.
Keywords Brittle fracture Failure analysis Heat-affected zone Steel
Analysis
Background The trunnion axle on the suspension assembly for the roadside of the front wing jeep on a multi-axle trailer failed, releasing the wheelset as shown in Fig. 1. It was determined that the trunnion axle, which acted as a hard suspension for the suspension assembly, separated near a weld attaching the trunnion axle to the round plate of the suspension assembly, as shown schematically in Fig. 2. The subject trailer was manufactured approximately two years earlier and sat unused until the time of the incident.
J. A. Lemberg (&) B. D. Ellis E. P. Guyer Exponent, Inc., 3350 Peachtree Road NE, Suite 1125, Atlanta, GA 30326, USA e-mail: [email protected] B. D. Ellis Mechanical Engineering Technology, University of Maine, 5711 Boardman Hall, Orono, ME 04469, USA
Following visual inspection and photo-documentation, the subject fractured trunnion axle was prepared for fractographic inspection via optical microscopy and scanning electron microscopy (SEM). Cross sections of the fracture surface were then prepared in general accordance with ASTM E3 for metallographic and microhardness analyses [1]. Chemical analysis of the axle material indicated that the axle conformed to AISI 1026, one of the alloys listed in ASTM A519 for cold-drawn seamless tubes [2]. The results of the chemical analysis are presented in Table 1. Fractographic analysis indicated that the failure propagated as the result of a single overload event and originated at what appeared to be a pre-existing flaw. Examination of the fracture surface revealed no obvious indications of fatigue or crack arrest, which suggests the fast fracture occurred during a single event. A representative photograph of the fracture surface is shown in Fig. 3. S
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