20 documents found, page 1 of 2
Failure analysis of cylinder head studs of a four stroke marine diesel engine
Fonte, M.; Reis, L.; Infante, V.; Freitas, M.After about seven years in service, four cylinder head studs, which tight the block and cylinder heads of a marine main engine, have fractured. Meantime, they were changed for new ones without to determine the root cause of failure. The aim of this research work is to carry out a failure analysis in order to avoid recurrent damages in that engine. The fracture morphology and thread roots of fractured studs were...
Failure mode analysis of a diesel motor crankshaft.
Fonte, M.; Infante, V.; Reis, L.; Freitas, M.A failure mode analysis of a diesel motor (110 kW) crankshaft from an automobile vehicle is presented. After 120,000 km in service, an abnormal vibration was detected which was increasing with the time. The diesel motor was first disassembled for determining the root cause, however without success. No defect was detected, but since a suspicion of damage was present, and being this failure recurrent in this type...
Failure mode analysis of two diesel engine crankshafts
Fonte, M.; Infante, V.; Freitas, M.; Reis, L.A failure analysis of two damaged crankshafts are presented: one obtained from a diesel engine of a mini backhoe, and another one from an automobile vehicle. The diesel motor suffered a serious mechanical damage after 3 years and 5000 hours in service: the connecting rod n° 3 broke and, in consequence, the crankcase and motor block suffered damage. The motor was repaired by a non-authorized workshop, but mainta...
Rotary fatigue testing to determine the fatigue life of NiTi alloy wires: an ex...
Carvalho, André; Freitas, Manuel; Reis, Luís; Montalvao, Diogo; Fonte, M.Endodontic rotary file instruments used to treat root canals in dentistry suffered breakthrough transformations in recent years when stainless steel was replaced by Nickel-Titanium (NiTi). NiTi alloys used in Endodontics possess superelastic properties at body temperature (37C) that bring many advantages on the overall performance of the root-canal treatment. They can follow curved root canals more easily than ...
Determination of the rotary fatigue life of NiTi alloy wires
Carvalho, André; Montalvao, Diogo; Freitas, Manuel; Reis, Luís; Fonte, M.Nickel-Titanium (NiTi) alloys with superelastic properties have been increasingly introduced as a substitute to more conventional alloys, such as stainless steel, in a variety of applications. In Dentistry, NiTi alloys are used in tools such as Endodontic rotary files, allowing the file to follow teeth root canals more easily than their stainless steel counterparts. Nevertheless, during surgery, the file is sub...
Rotary fatigue testing machine to determine the fatigue life of NiTi alloy Wwre...
Carvalho, André; Freitas, Manuel; Reis, Luís; Montalvão, Diogo; Fonte, M.Endodontic rotary file instruments used to treat root canals in dentistry suffered breakthrough transformations in recent years when stainless steel was replaced by Nickel-Titanium (NiTi). NiTi alloys used in Endodontics possess superelastic properties at body temperature (37C) that bring many advantages on the overall performance of the root-canal treatment. They can follow curved root canals more easily than ...
Crankshaft failure analysis of a boxer diesel motor
Fonte, M.; Anes, V.; Duarte, P.; Reis, L.; Freitas, M.This paper reports a failure mode analysis of a boxer diesel engine crankshaft. Crankshafts are components which experiment severe and complex dynamic loadings due to rotating bending combined with torsion on main journals and alternating bending on crankpins. High level stresses appear on critical areas like web fillets, as well as the effect of centrifugal forces and vibrations. Since the fatigue fracture nea...
Failure mode analysis of two crankshafts of a diesel single cylinder engine
Fonte, M.; Duarte, P.; Reis, L.; Freitas, M.; Infante, V.This paper reports an investigation carried out on two damaged crankshafts of single cylinder diesel engines used in agricultural services for several purposes. Recurrent damages of these crankshafts type have happened after approximately 100 h in service. The root cause never was imputed to the manufacturer. The fatigue design and an accurate prediction of fatigue life are of primordial importance to insure th...
Welding assessment of a damaged crane pedestal of a container ship
Fonte, M.; Freitas, M.M.; Li, B.; Duarte, P.; Reis, L.A structural integrity assessment of a damaged crane pedestal/column of a container ship is presented. Crane cabins and pedestal/columns are subjected to fatigue coupled with sudden overloads during cargo operations and corrosion effects due to sea environment. Significant number of surface cracks was detected around the pedestal/column, at inner and outside of the crane foundation, close to the main weld seam ...
On the assessment of fatigue life of marine diesel engine crankshafts
Fonte, M.; Duarte, P.; Anes, V.; Freitas, M.; Reis, L.The fatigue strength and its correct assessment play an important role in design and maintenance of marine crankshafts to obtain operational safety and reliability. Crankshafts are under alternating bending on crankpins and rotating bending combined with torsion on main journals, which mostly are responsible for fatigue failure. The commercial management success substantially depends on the main engine in servi...