May 16, 2020

Half of British engineers receive just five days of training a year

engineers
construction
Manufacturing
bosch rexroth
Nell Walker
2 min
Half of British engineers receive just five days of training a year
Bosch Rexrothis calling on the construction and manufacturingindustriesto invest more in maintenance training following the results of a recent study...

Bosch Rexroth is calling on the construction and manufacturing industries to invest more in maintenance training following the results of a recent study.

The survey conducted amongst 300 engineers by Bosch Rexroth, in conjunction with The Institution of Engineering and Technology (The IET), revealed that more than 50 per cent of engineers receive only five days training or less each year. A mere 12 per cent said they were entitled to 10 or more training days.

One of the key issues, backed by approximately 75 percent of respondents, highlighted the rise in increasingly complex equipment, with maintenance teams struggling to keep up. Despite this increase in complexity, more than half confirmed training budgets had stagnated or decreased.

“It seems like a simple equation that training should intensify as manufacturing technology advances but this is something easier said than done” said Richard Chamberlain, UK Service Manager at Bosch Rexroth.

Richard continued: “It’s crucial that those responsible for machine uptime remain up-to-speed with new technologies. However, with a chronic shortage of skilled technicians, the stigma that training takes engineers away from their core responsibility, is still a legitimate problem.”

“Looking at the report, it is encouraging to see that almost half of respondents declared e-learning courses were key in their training and these are likely to increase as machines get increasingly interconnected. It’s essential that effective training is in place to support engineers; by remaining up-to-speed with advancing technology this will in turn ensure machines run as smoothly and efficiently as possible.”

A detailed analysis of the survey has been compiled into a paper. ‘What you don’t repair you destroy – A report into maintenance practices in UK Industry’ can be downloaded from here

 

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Jun 17, 2021

Why engineers must always consider human-induced vibration

Vibrations
Engineering
design
Structuralintegrity
Dominic Ellis
3 min
Human-induced vibration can lead to a number of effects upon the structure and its users

Human induced vibration, or more accurately vibrations caused by human footfall, often conjures images of Millennium Bridge-style swaying or collapsing buildings.

But in reality, the ‘damage’ caused by human-induced vibrations is less likely to ruin a structure and more likely to cause discomfort in people. Though not as dramatic as a structural failure, any good engineer wants to make sure the people using their structures, be it bridges or buildings or anything in between, can do so safely and comfortably. This is why human-induced vibration must be considered within the design process.

Resonance v Impulse

There are two ways that human-induced vibrations affect structures: resonant, and impulse or transient response. Put simply, resonance occurs when Object A vibrates at the same natural frequency as Object B.

Object B resonates and begins to vibrate too. Think singing to break a wine glass! Although the person singing isn’t touching the glass, the vibrations of their voice are resonating with the glass’s natural frequency, causing this vibration to get stronger and stronger and eventually, break the glass. In the case of a structure, resonance occurs when the pedestrian’s feet land in time with the vibration.

On the other hand, impulse or transient vibration responses can be a problem on structures where its natural frequencies are too high for resonance to occur, such as where the structure is light or stiff. Here the discomfort is caused by the initial “bounce” of the structure caused by the footstep and is a concern on light or stiff structures.

Engineers must, of course, design to reduce the vibration effects caused by either impulse or resonance.

Potential impacts from human induced vibration

Human induced vibration can lead to a number of effects upon the structure and its users. These include:

  • Interfering with sensitive equipment Depending on the building’s purpose, what it houses can be affected by the vibrations of people using the building. Universities and laboratories, for example, may have sensitive equipment whose accuracy and performance could be damaged by vibrations. Even in ordinary offices the footfall vibration can wobble computer screens, upsetting the workers.
     
  • Swaying bridges One of the most famous examples of human-induced resonance impacting a structure occurred with the Millennium Bridge. As people walked across the bridge, the footsteps caused the bridge to sway, and everybody had to walk in time with the sway because it was difficult not to. Thankfully, this feedback can only occur with horizontal vibrations so building floors are safe from it, but footbridges need careful checking to prevent it.
     
  • Human discomfort According to research, vibrations in buildings and structures can cause depression and even motion sickness in inhabitants. Tall buildings sway in the wind and footsteps can be felt, even subconsciously by the occupants. It has been argued that modern efficient designs featuring thinner floor slabs and wider spacing in column design mean that these new builds are not as effective at dampening vibrations as older buildings are.
     
  • Jeopardising structural integrity The build-up of constant vibrations on a structure can, eventually, lead to structural integrity being compromised. A worse-case scenario would be the complete collapse of the structure and is the reason some bridges insist that marching troops break step before crossing. Crowds jumping in time to music or in response to a goal in a stadium are also dynamic loads that might damage an under-designed structure.

How to avoid it

As mentioned, modern designs that favour thinner slabs and wider column spacing are particularly susceptible to all forms of vibration, human-induced or otherwise, but short spans can also suffer due to their low mass. Using sophisticated structural engineering software is an effective method for engineers to test for and mitigate footfall and other vibrations at the design stage.

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