Everything
in the world wobbles. Some things wobble on a visible scale, such as bridges
and vehicle suspension; while other things wobble on a microscopic scale, such
as the molecules in a metal saucepan on your induction hob. In this
presentation we see why things wobble; why they like to wobble at a preferred
frequency known as the ‘natural’ (or resonant) frequency. We see how just a
tiny amount of energy applied at the right frequency leads to a huge response.
This is used to good effect in the microwave oven; but it’s also the cause of
countless engineering failures. So how do we design structures to absorb
dynamic loads and how do we avoid catastrophic failure through resonance?
• Why things
wobble
• Wind turbine
tower
• Car
suspension – mass, spring and damper
• Multi-storey
buildings & bridges
• Random
vibration – wind, waves and roads
• Helicopter
vibration
• Engine
vibration – gears & bearings
• Offshore
structures
• Non-linear vibration – Chaos theory
Dr. Andrew Halfpenny heads R&D activities at nCode working
in areas of defence, automotive, aerospace, civil engineering, and power
generation. nCode is a software product used for fatigue and durability design,
from CAE concept design through full-scale testing and fleet durability
monitoring. Over the years Andrew has introduced many new technologies
including shock and vibration qualification processes used by AgustaWestland
and Structural Health Monitoring techniques used by the US and UK military. He
has worked in consultancy with customers across the UK, Europe, Americas and
the Far East and has written publications on Fatigue, Digital Signal Processing
and Structural Health Monitoring. He sits on the NAFEMS committee for Dynamic
Testing and is a guest lecturer on structural dynamics and fatigue with several
academic institutions.
