Failure of two overhead crane shafts

The failure analysis of two overhead crane shafts is presented: the failure of an overhead crane drive shaft and the failure of an overhead crane gearbox shaft, due to rotating-bending fatigue. The fracture of the overhead crane drive shaft originated in small radius fillet between two different diameters of the shaft. A new shaft was made with a larger-size fillet, resulting in reduced stress concentration in this region. The failure of the overhead crane gearbox shaft originated in the intersection of two stress raisers, due to a change in the shaft diameter and in the keyway corner. A new shaft was made with a larger-size fillet and a larger size radius of the keyway corner to minimize stress concentration in this section. In both cases the installed couplings were replaced by gear couplings in order to allow parallel and angular misalignment as well as to avoid additional load due to misalignment. The analysis shows that the fatigue life can be significantly increased with a simple change in the structural detail

Failure analysis of the rolling mill stand coupling

The failure analysis of two slipper couplings showed that both couplings fractured as a result of fatigue. In both cases, the fracture started in the corner between the paddle and the coupling body and propagated around the corner. Both fractures were caused by the deficient design of the fillet between the paddle and the coupling body with high stress concentration. In order to extend actual service life, three design modifications were considered. Numerical analysis showed that the redesign of the coupling with stiffener between the paddle and the coupling body reduced maximum local and actual service life of couplings and can be improved from finite to infinite

The Application of Pulsed Thermography Image Processing Method to Longwave Bolomteric Infrared Cameras

Pulsed infrared thermography is a NDT method for evaluating polymer reinforced structures. As our former research was performed on advantageous cooled middle-wave camera, in this contribution gradient based image processing method has been applied on long-wave bolometric cameras. Different wavelengths and camera sensitivities have been compared on prefabricated specimen. To demonstrate the capability of approach, examples from floating vehicles industry have been presented

Fatigue Failures in Industry and Their Repairs – Case Studies

In spite of numerous and expensive researches in the field of fatigue, cracks and failures caused by fatigue occur every day in all fields of human activity. The paper presents some typical fatigue damages in industry and transport. Fatigue failure of the main engine lateral support (at bulk carrier), fatigue cracks on the large portal crane, and fatigue cracks and failures of the large gear wheel of the cement mill are described. The complete fatigue damage analysis and repair procedures are presented, too

Failure analysis of the rolls with grooves

he failure analysis of the rolls with grooves on the 3-high-roughing mill stand for hot rolling is presented. Detailed analysis of all the elements which influenced the failure was carried out, namely: the position and the place of all failures are determined and all fracture surfaces are described; the rolling forces are determined by analytical and experimental methods; numerical analysis of the local stresses due to rolling forces is performed with finite element method; stress time history of the individual local stress and stress spectrum are obtained from service loads; prop- erties of the roll material (strength, hardness, toughness and ductility) is determined by experimental testing. Based on the results of investigation, main causes of failures are presented

Fatigue Failures in Industry and Their Repairs – Case Studies

In spite of numerous and expensive researches in the field of fatigue, cracks and failures caused by fatigue occur every day in all fields of human activity. The paper presents some typical fatigue damages in industry and transport. Fatigue failure of the main engine lateral support (at bulk carrier), fatigue cracks on the large portal crane, and fatigue cracks and failures of the large gear wheel of the cement mill are described. The complete fatigue damage analysis and repair procedures are presented, too

The Application of lR Thermography to the NDT and Thermal Stress Analysis

Advantages of using Infrared Thermography as a Non Destructive Testing method is resulting in the growing interest for method in the field of composite structures. The presented research is focused on Glass Reinforced Polymer structures. Methods, such as Pulse Thermography, Pulsed Phase Thermography and Lock-in Thermography are re-ferred. The Pulse Thermography together with the gradient based approach is addressed for the case of wind turbine blades. The gradient based image processing approach enables filtering out anomalies with the goal to make clearer distinction and evaluation. The Ther-moelastic Stress Analysis, as a method similar to the Lock-In Thermography, is presented as an NDT approach for evaluating stress distribution of cyclic loaded structures

EKSPERIMENTALNA PROCJENA KONSTRUKCIJE BRODSKIH MOTORA

Mjerenja pomoću elektrootporničkih traka primijenjena su kod analize ključnih dijelova novih brodskih motora. Prikazana su dva karakterisična primjera i to: analize naprezanja i uzroka oštećenja na bočnim uporama glavnog motora te analize naprezanja i procjene vijeka trajanja temeljne ploče glavnog motora brodova za rasuti teret

Fatigue Strength of the Rolls with Grooves

Abstract. In "Steelworks Split" failures of the rolls with grooves on the 3-high-roughing mill stand occurred four times. Detailed analysis of all the elements which influenced the failure was carried out. Stress analysis shownthatthe most critical area of the roll is the 7.a caliber what is corresponding with fracture positions. The fatigue strength of the material in the caliber groove for fatigue life prediction was missing and fatigue strength is determined by experimental testing