Finished Product

An animation of the final product.

Toppling

The main problem with a hoist crane is the need for large counter weights. There will be an allocated zone for the counter weight that can be picked up from the disaster area. A counter weight is only needed when lifting over 650kg (711kg actual); in a case where over 1000kg (up to 1200kg) is lifted a counter weight of 600kg is needed. Iron counter weights will be supplied but debris can be used. The table below shows the counter weight required when lifting larger masses:

Analysing Stress on Main Beam

For the team to decide on a material we need to know which criteria need to be met. The design involves a large beam that will take the majority of the load and will be supported by cables and smaller beams. In some cases the calculations can be made and a suitable material can be found, or the type of beam can be used with a single material chosen first. As the material specialist has not been available to aid this decision the team have worked together and decided on plain carbon steel for the build. Plain carbon steel is a very versatile and cost effective material. We can reduce the size of the beams without compromising strength and hence reduce weight.

To carry out the initial stress analysis I have used SolidWorks, however, the loads have been exaggerated to account for material defects, modelling errors and over working. The results show that the main beam will take the load with a stress of 220.59GPa where the yield stress of steel is about 280GPa. The final design will have support beams and cables so the maximum experienced stress will be noticeably smaller.

Final testing will be carried out by Onwell, the design engineer.

After testing various beam types and size from the SolidWorks ‘Toolbox’, this beam (dimensions below, found on http://www.franklinsteelplc.co.uk/steel/unibeam.htm) is the best suited for the task.

Lifting a One Tonne Load

The crane will need to be able to lift a 1000kg load and move it 4m, with no guaranteed source of electricity the only source of power will be manual. For a small group of people, the one tonne load can be easily managed using a pulley system as mentioned under ‘Pulley Design’. Even with a 6 to 1 pulley system a two person team will need to each move the equivalent of 83.3kg by 6m to raise the load just 1m off the ground, that’s almost the same as carrying a person up a single flight of stairs. Using a winch, the turning force generated can be multiplied to reduce the effort a 5th of the original work needed.

The winches available on the market will vary from the design shown so the force that will need to be applied will also vary. The calculations are based in an ideal situation and in reality they will be much greater. Factors such as friction, temperature, humidity, strength of the individuals and the elasticity of the cable will need to be accounted during the second design phase.

Initial Design

Below is an initial design for the crane. It is loosely based on the engine hoist but with a fixed arm and vertical legs. This should make it more stable in theory and some calculations will be made at a later date to find the idea position and mass of the counter weight.

Gant Chart

Brainstorming

Bellow are some general ideas brought up in the last meeting. The first image shows a guide to the design criteria set out by Emerging Engineering

click to image enlarge

Here are some of the types of cranes and hoisting systems researched. (the size of image and arrows reflect the team's interest towards the design)

click image to enlarge

Summary of meeting 9th March 2010

Attendees
Raj
Ramazani
Onwell
Stefan
Moshin

Meeting Outcome

• All team members issued roles
• Discussed portable cranes on the market and compared prices and practicality

Team Members’ Roles

• Project Manager - Stefan
• Finance Officer - Rama
• Chief Designer - Onwell
• Stress Analyst - Raj
• Materials Specialist - Mohsin
  

Next Meeting

• The next meeting will be on Wednesday 17th March in the Loft.
• Meetings will be held at least once a week.

Summary of meeting 5th March 2010

Attendees
Raj
Rama

Absences
Onwell (reason - interview)
Stefan
Moshin

Meeting Outcome

• The team had set up a blog on http://megroupg.blogspot.com/ which is open to all to view.
• Preferred roles were discussed and chosen by Raj and Rama. The remaining members will have roles by Tuesday.

Team Members’ Roles
So far the roles of team members are:
Rama – Co-ordinator and Finance Officer
Raj – Stress Analyst

Tasks before Next Meeting
Rama

• Email Dr Thomson about blog site and team members’ roles on Tuesday after the meeting*.
• Research cost of similar product on the market
  

Raj

• Research cost of material
• Find possible materials suitable for the job and their properties

Moshin, Onwell and Stefan

• Think of a role you will best fit in the team.

*Next Meeting

• The next meeting will be on Tuesday at 5pm in NG09.
• Members will need to choose roles in the team.