Finite element analysis and structural optimisation of a concrete mixer

  • Peter Macdonald

Student thesis: Master's Thesis

Abstract

The UK concrete transport industry desires low weight concrete mixers in order to maximise payload. To investigate the potential for weight reduction of the mixer unit itself, three key structures of a particular mixer have been analysed using Finite Element Analysis; the front drum support structure, rear drum support structure, and the sub-frame.A full scale ‘dynamic load test’ has been documented. This involved recording data from 20 strain gauges and 2 accelerometers attached to a concrete mixer. The three main load cases investigated during this test were bump/pothole loads, braking loads, and ‘downhill’ loads. The results are presented and discussed with a view to understanding the load paths through the whole structure. The data has provided a solid foundation for future work which could focus on specific areas. A test to investigate the differences in elastic properties of holding down U-bolts versus straight bolts has also been documented as these components facilitate the main load path between the supports and the chassis. Recommended practices for implementing a Design by Analysis process are discussed.A redesign of the front drum support has allowed two sub-frame stiffening plates to be removed. This revised front support is 21% lighter than the combination of the existing front support and the stiffening plates. An optimisation study of the existing rear drum support has resulted in a reduction in the weight of this structure by 26%. The sub-frame was not lightened due to this being difficult to achieve without decreasing stiffness, which is already relatively low. However, some basic analysis has been done to examine the design of the brackets that secures the sub-frame to the chassis.This work has shown that there is scope to reduce the weight of truck-mounted concrete mixers.In this industry, applying a comprehensive Design by Analysis process would significantly increase the profits achievable by companies involved in the transport of concrete. Concrete mixer manufacturers and similar SME’s should consider this approach; however it must be ensured that the capabilities of FEA are fully understood before making a business case. Furthermore, it is vital to the success of the process that the engineers using the software are suitably trained or experienced.
Date of Award1 Dec 2014
LanguageEnglish
Awarding Institution
  • University Of Strathclyde
SupervisorDavid Nash (Supervisor) & Barbara Keating (Supervisor)

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