Softwood Timber Degradation, Non-Destructive Testing, and Sustainability Assignment Instructions

Task 1: Softwood Timber Degradation, Non-Destructive Testing, and Sustainability

1. Describe the basic properties of steel, concrete & timber relate to their production and use.
2. Describe the properties of building materials and understand their performance characteristics with regard to the natural environment and fire.

You will need access to a PC or mobile device with access to the Internet.

The work should be your own work and not copied or downloaded from any other source.   

To ensure that your work is original and valid the text submitted in the online test will be submitted to Turnitin to check for collusion and plagiarism. 

You are prepared to agree to the following “By submitting this work I can confirm that it is my work only and has not been copied from any other source or that I have collaborated with any third party in preparing my responses. I am willing to undergo a viva with my assessor to confirm the validity of my work.” 

Instructions to students

Marks will be awarded for presentation, grammar, spelling, clarity of descriptions and showing good communication skills.

Task 1

One of the most important materials used in construction today is Softwood Timber. However, Softwood timber is not a durable a material.

I.Describe and explain the degradation of softwood timber due to Dry and Wet rot.

II.Timber is an organic material and as such requires a non-destructive test to determine Youngs Modulus of stiffness. Describe such a test and discuss its usefulness in assessing strength.

III.Discuss the role of timber materials in a sustainable world.

Task 2

In an experiment, Youngs modulus for softwood timber (a copy is included in Appendix 1) the following data was collected. (Table 1)

I.Draw a graph using the line of best fit of load against deflection. The load should be on the vertical axis and the deflection on the horizontal axis. Your graph should have a title and should show the scales on both axis’s. Both the loading and unloading deflections should be drawn on the same graph.

II.Discuss why the lines on the graph do not coincide and the effect of this on a timber beam.

Clearly, the Young’s modulus of the cell wall is a lot higher than that of wood, as the cells and spaces in the wood filled by air or water also affect wood’s Young’s modulus, shows viscoelastic properties under deformation. Viscoelasticity is advantageous, not least because it dampens vibrations: in high winds damping of resonance protects the branches and trunk from excessive deflections associated with damage. A stiff material could also limit deflections, but at the expense of high stresses. Overall, it is preferable to be able to bend. The origins of wood’s viscoelastic behaviour lie in the lignin matrix. Lignin is an amorphous polymer, and its elastic regions respond instantly to the strain while the viscous regions respond more slowly. Due to this viscoelasticity, energy is dissipated in the wood on loading. On the graphs the area between the loading and unloading curves shows the elastic strain energy that is being stored in the wood. However the amount of energy is not high enough to cause problems. In living trees, in particular, the high water content of the wood inside the cells and extracellular matrix restricts a significant temperature rise, because of the high heat capacity of water.

• How accurate was the experiment and how can you improve it.
• Compare your results with the generally accepted values for E
• Discuss the importance of Young’s modulus of elasticity in relation to its use in  structural design
• Describe a system for stress grading of timber