W&E Platt Pty Ltd tendered for the development of a replacement for the existing 50 Cal
machine gun mount used on the M113A1 armoured personnel carrier. As part of the qualification
of their proposed softmount design they were required to conduct performance testing and finite
element analysis. Vipac Engineers & Scientists Ltd was commissioned by W&E Platt Pty Ltd
to conduct a series of strain gauge tests to determine softmount performance, static strength
and fatigue finite element analysis.
The performance testing involved the development of a test specification and conduct of the test.
The objectives of the performance tests were to determine:
I. the recoil attenuation produced for single and multiple rounds,
II. transmitted loads to weapon supports,
III. gun travel during operation,
IV. develope a gun load firing spectrum.
The softmount and test fixture were comprehensively strain gauged and accelerometers were
mounted at specific locations. Tests were conducted for different configurations involving
different combinations of multiple round bursts of gun fire at a number of different elevations.
The results from the performance testing were used to construct a gun firing load spectrum and to determine
the stress distribution for verification of the finite element analysis. The Finite Element Analysis
was performed to facilitate a static strength and fatigue analysis. The studies were conducted
in accordance with a combination of accepted design practises and the Australian Standards for
Steel and Aluminium limit state design. All of the components of the softmount were included
in the study, i.e. recoil springs, bearing blocks, fasteners, etc.
