A study on diesel engine crankshaft bearing failure analysis with consideration of bearing lubrication

Purpose The edge of diesel engine crankshaft main bearing is more likely to fail in its real working condition. This paper aims to study the bearing failure mechanism by finding the relationship between bearing lubrication characteristics and its working condition. Design/methodology/approach This work builds the mixed lubrication model of crankshaft bearing to analyze the cause of bearing abnormal wear, and the finite difference method was used to solving the average Reynolds equation. During the analysis, journal misaligned angle, external load and roughness are considered. Findings The result shows that the wear of the diesel engine crankshaft bearing happens in engine startup phase and the bottom of the bearing are more prone to be excessively worn. Under the influence of journal misalignment, bearing asperity contact load and speed range of mixed lubrication will increase markedly. The edge of the bearing will be excessively worn. The effect of misalignment on bearing lubrication performance varies under different shaft rotation speed. Originality/value The former research studies on crankshaft bearing either just focused on its lubrication characteristics or interested in its failure types (wear, adhere, cavitation). This paper studies the relationship between bearing failure mechanism and lubrication performance.

Engine Oil- Crankshaft Interaction Fem Modelling of an Air-Cooled Diesel Engine under Dynamic Severe Functioning Conditions

Taking into account the interaction between the engine oil and the crankshaft to model crankshaft thermomechanical behavior under dynamic loading is very important. In particular, when the crankshaft is working in severe conditions. This paper deal with an air cooled direct injection-type engine crankshaft thermomechanical FEM modelling account for engine oil-cranks half interaction in severe working conditions. As case of application we consider the diesel engine Deutz F8L413. The model takes into account 2 forced convectives heat flux: engine oil and crankcase air. The severe mechanical and thermal characteristics of engine are experimentally measured on a bench test equipped with a hydraulic brake. The temperature distribution inside the crankshaft was computed using the measured temperature as boundary conditions. The most thermo-mechanical stressed zones of the crankshaft have been determined. The fatigue resistance of the crankshaft under thermo-mechanical conditions was examined using Dang-Van multi-axial fatigue criteria. To prove our model efficiency, we have compared crankshaft damage in service to the numerical simulation results. It was found the breakage occurred in an area where the numerical simulations give the highest stresses.

SIMULATION OF A DUAL CLUTCH AUTOMATED TRANSMISSION GEAR SHIFT

A computer dynamic model of an automobile transmission with a double dry clutch, created using the "Universal Mechanism" software package, is presented. Work objective is to analyze the possibility of improving double dry clutch efficiency at various controls of compressive forces of clutch plates. The computer model contains 7 bodies: an engine crankshaft, two clutch plates, two gearbox input shafts for odd and even gears, an output shaft, a fly wheel. The simulation of gear shifting shows that pressing a clutch pedal or letting out the clutch simultaneously, cutoff time increment increases the rotational speed justification of the engine shaft and the input shaft of the actual gear, the total work of the friction forces of both clutches and does not affect the maximum value of clutch plates rotary sliding resistance. Frictional energy of the clutch when shifting gears from lower to higher is greater than when shifting gears from higher to lower. Sequential clutch on-off reduces the total frictional energy of both clutches by 1.17...1.31 times compared to simultaneous one. The model allows looking into different gearshift modes with uniform velocity or accelerated vehicle motion, optimize the gearshift strategy.

On problem of calculating longitudinal vibrations of piston engine crankshaft

One of the initial stages of calculating the crankshaft longitudinal vibrations is developing an oscillatory system model, which includes the determination of longitudinal pliability (rigidity) of elastic sections. If it is impossible to determine the pliability experimental, the empiric formulas or the final element method (FEM) are used. There are given the values of crank longitudinal pliability of the crankshafts of different marine engine types found by using the formulas of L. Gugliemotti – R. Machciotta, P. Draminsky, E. Y. Gorbunov, S. F. Dorey, N. S. Skorchev, V. S. Stoyanov, etc. It is shown that the calculation results obtained from these formulas for the same engine significantly differ; therefore, the choice of one or another empirical formula for practical calculations is difficult. The preference of using FEM for determining the longitudinal (axial) compliance of cranks and other areas with complex geometric shapes has been proven. The possibility of its application is also shown to determine the longitudinal disturbing force as the reaction of the crankshaft support against the action of the radial force exerted to the connecting rod journal. It is proposed to use, along with empirical formulas, regression equations connecting the longitudinal compliance of the cranks with a significantly larger number of their design dimensions.

Description of acid battery operating parameters

The principles of acid battery operating and its features are discussed. The tests results of voltage measured at the terminals of a loaded battery under constant load conditions dependence on time have been presented. The principles of acid battery electric models creating and various possibilities of its description are presented. The principles of processing the results for the purpose of determining and describing the battery model are characterized. The possibilities of description of the characteristics under stationary and non-stationary conditions by means of glued functions, linear combination of exponential functions and determination of electrical parameters of the battery as components of the circuit, i.e., its electromotive force, resistance and capacity are indicated. The signals recorded during the cranking of the engine crankshaft by the starter are discussed. There are indicated the possibilities of using the crankshaft driving signals as diagnostic signals of the battery, electric starter, and internal combustion engine.

Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students

This book is a unique blend of history, technology review, theoretical fundamentals, and design guide. The subject matter is primarily piston aeroengine superchargers – developed in Germany during the Second World War (WWII) – which are centrifugal compressors driven either by the main engine crankshaft or by an exhaust gas turbine. The core of the book is an unpublished manuscript by Karl Kollmann, who was a prominent engineer at Daimler-Benz before and during the war. Dr. Kollmann’s manuscript was discovered by Calum Douglas during his extensive research for his earlier book on piston aeroengine development in WWII. It contains a wealth of information on aerothermodynamic and mechanical design of centrifugal compressors in the form of formulae, charts, pictures, and rules of thumb, which, even 75 years later, constitute a valuable resource for engineering professionals and students. In addition to the translation of the original manuscript from German, the authors have completely overhauled the chapters on the aerothermodynamics of centrifugal compressors so that the idiosyncratic coverage (characteristic of German scientific literature at that time) is familiar to a modern reader. Furthermore, the authors added chapters on exhaust gas turbines (for turbo-superchargers), piston aeroengines utilizing them, and turbojet gas turbines. Drawing upon previously unpublished material from the archived German documents, those chapters provide a concise but technically precise and informative look into those technologies, where great strides were made in Germany during the war. In summary, the coverage is intended to be useful not only to history buffs with a technical bent but also to the practicing engineers and engineering students to help with their day-to-day activities in this particular field of turbomachinery.

Dynamic Behavior of the Full-Car Model in the J-Turn Maneuver by Considering the Engine Gyroscopic Effects

This study presents a new dynamic modeling of a vehicle by considering the engine dynamics. By selecting the vehicle coordinate system as the reference frame, all the force-torque equations of the sprung mass and unsprung masses are derived in this coordinate system by using the Newton’s equations of motion. Unlike the previous researches, in this work the sprung mass of the vehicle is not considered as a rigid body. The dynamics of the sprung mass components, such as gyroscopic effects of the engine crankshaft, is considered. In order to study the vehicle's dynamic behavior, in the J-turn maneuver, the governing equations of the full-car model are evaluated and validated by the numerical simulation method and ADAMS/Car software. Based on the results, the maximum roll angle and roll rate of a vehicle reach about 8 degrees and 40 degrees per second, respectively.

The torsional vibration simulation of the diesel engine crankshaft system based on multi-body dynamic model

In order to analyze the torsional vibration of the crankshaft system, a three-dimensional model of the crankshaft system is established, consisted of the piston, connected rod, crank shaft, flywheel and silicone oil damper. Use by multi-body dynamics simulation software ADAMS, created the multi-body dynamics model of the multiple degrees of freedom consisting of rigid hybrid engine system, to do the torsional vibration response simulation, analysis of the torsional vibration on the crankshaft. Through the torsional vibration test of the diesel engine crankshaft system, the accuracy of the simulation calculation results have been verified. This simulation result has higher accuracy, and this calculation method has certain engineering application value.

Failure Analysis of a Diesel Engine Crankshaft

A six-cylinder crankshaft in a 12L diesel engine was locked after testing for about 840 hours in the bench test. The fractography investigation indicates that fatigue is the dominant failure mechanism of the crankshaft. It is found that the fatigue crack mainly initiated at the fillet of the crankweb between the 6th main journal and 6th crankpin. The fatigue crack initiation area lies outside the induction surface hardened zone. From detailed metallographic inspection, abnormal microstructure containing Widmannstatten was found in the fatigue crack initiation area and the 5th main journal, while that was not found at the severely deformed crankweb. Since the region containing Widmannstatten has lower hardness, the root cause of the failure may be that the abnormal microstructure lowered the fatigue strength at the stress concentrated fillet. The crankshaft prematurely fractured under the complex stress condition in the bench test.