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David Kirkaldy was born near Dundee in Scotland in 1820. He worked at Robert Napier’s Vulcan Foundry Works in Glasgow where he developed several ideas for testing the reliability of metals supplied by local foundries – leading to a book, published in 1862 – An Experimental Inquiry into the Comparative Tensile Strength and other properties of various kinds of Wrought-Iron and Steel
His masterpiece was the Kirkaldy Testing Machine – a monster of a device that is 47 feet long and weighs 116 tons.
 The reason it was so massive is that testing in the early days was not carried out on samples of materials – but on actual finished products. Metals were still fairly impure – by modern standards – so testing was carried out on final finished units and it was presumed that along the length of a piece of steel or concrete, the imperfections would be roughly the same for all components. Today, the purity of materials is such that only tiny samples are really needed for testing.
MUSEUM
David Kirkaldy constructed a custom designed building – with the main testing machine on the ground floor, a basement with secondary testing equipment and the pumps for the hydraulic water to power the machine (later powered by the London Hydraulic Power Company) and upper floors for storing used test samples and offices. The upper floors are now offices, the ground floor has been given over to the museum (a legal ruling preserves it almost forever in that venue) and the place is open on the first Sunday of the month to visitors.
Once you get to the museum, there is a small sign directing you to go round the back, and there you will find a locked door with a small sign and a doorbell. Ring and someone will come to let you in. As the building is still a working environment to some degree, they can’t just leave the door open for people to wander around the place unescorted.
APPLICATION
Kirkaldy famously tested many samples taken from the first Tay railway bridge for the official Inquiry on the Tay Bridge Disaster. He confirmed that the wrought iron tie bars failed at their connections to the cast iron columns of the bridge, when he tested intact tie bars with complete lugs still attached. The attachments were cast iron lugs which fractured at the bolt holes, and numerous fractured lugs were found after the disaster lying on the piers. The critical strengthening elements were much weaker than had been supposed by Thomas Bouch, the engineer of the first bridge. They failed at about 20 tons tensile load rather than the specified 60 tons, and were a prime cause of the collapse of the bridge on 28 December 1879.
Since Kirkaldy tested several samples of each of the lower and upper lugs, he was able to show that they exhibited a range of strengths, the lowest results being caused by defects like blow holes in the cast metal. Thus some of the upper lugs were actually weaker than the strongest lower lugs, an observation confirmed by damage shown on the remains left on the piers after the disaster. He tested the wrought iron tie bars themselves, and they proved tough, as specified, although only slightly stronger than the cast iron lugs to which they were attached. The high girders were also made of wrought iron and had a very high tensile strength. They were found after the accident at the bottom of the Tay estuary and had sustained relatively little damage compared with the cast iron columns which supported them.
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