No abstract

Bucket is key and primary component of heavy construction machinery such as excavators. It has to bear high impact loads during digging process, resulting in large stress and deformations. This research work has been focused on reducing stress and deformations produced in excavator bucket due to digging. For this purpose, different design patents of excavator buckets (including ornamental designs) were considered. Various models of excavator buckets were developed by varying geometrical parameters such as number of blade teeth/tips and bucket curvature. Finite element analysis of these models was carried out by using ANSYS in order to determine stress and strains. Maximum values of Von Mises stress, principal stress, factor of safety and total deformation were evaluated numerically for all three-dimensional geometric models. Excavator bucket with least values of stress and deformations, but largest factor of safety, was identified through numerical computations. Mechanical performance of ornamental buckets having quarter circular curvature with 6 blade teeth was observed to be better as compared to designs having single blade strip or 5 blade teeth. Mass reduction up to 2.5%, while the stress reduction and factor of safety enhancement up to 9.6% was achieved by incorporating 6 blade teeth in ornamental design of excavator bucket.

Ultrasonic horn is utilized in order to enhance the amplitude of vibration transmitted by the transducer in an ultrasonic machining system. It plays a vital role in vibration amplification to a magnitude suitable for efficient machining of materials. Ultrasonic machining system has to operate at a frequency of at least . Therefore, horn may be subjected to high magnitude of stresses leading to failure. Mechanical horn is designed to get optimum vibration amplification while keeping stresses in acceptable limits. In this research an ultrasonic compound horn was designed with through cutout of uniform diameter. The performance of ultrasonic horn was observed by varying the cutout diameter by modelling horns of four different materials: titanium, aluminum, steel and stainless steel respectively. Modal analysis was performed for computing modal frequencies in the axial direction, whereas harmonic analysis was carried out in order to determine vibration amplitude, stresses and factor of safety. The effect of varying frequency ratio on vibration magnification, stresses, and factor of safety were also investigated. The axial modal frequency was observed to increase, whereas amplitude of vibration and stresses were observed to decrease by increasing the cutout size. Titanium was found to be the most suitable material for ultrasonic horns, because it provided up to 159.4 % more amplitude of vibration and 3 times higher safety factor thus operating life as compared to other materials.

No abstract