| Kirkaldy Testing Museum | |
|---|---|
| Established | 1983 |
| Location | 99 Southwark Street, Southwark, London, England |
| Public transit access | Southwark |
| Website | None |
The Kirkaldy Testing Museum is a museum in Southwark, south London, England, located on the site of David Kirkaldy's testing works. It houses Kirkaldy's huge testing machine, along with many smaller more modern machines. It is open on the first Sunday of each month.
Kirkaldy worked at Napier shipworks, but left in 1861 and over the next two and a half years studied existing mechanical testing methods and designed his own testing machine. William Fairbairn had pioneered tensile strength measurement as well as assessing creep and fatigue on large structures as well as small. Entirely at his own expense, Kirkaldy commissioned this machine from the Leeds firm of Greenwood & Batley, closely supervising its production. Aggrieved over the slow rate of manufacture, after fifteen months he had it delivered to London still unfinished, in September 1865.
The testing machine is 47 feet 7 inches long, weighs some 116 tons, and was designed to work horizontally, the load applied by a hydraulic cylinder and ram. The working fluid is water not oil. The load is measured by a weighing system consisting as a number of levers with the final one carrying a jockey weight. When in use the operator lets water into the hydraulic cylinder and as the pressure and hence load on the test piece increases the jockey weight is wound along to balance the hydraulic load. As it is wound it moves over a graduated scale and when the object under test fails the number on this scale is noted and multiplied by the weight to give the failure load. The weight can be varied in increments of 50 pounds using slotted plates on a hanger. On the lower scale this reads up to 150 and up to 1000 pounds can be put onto the hanger. A separate jockey weight system above this one allowed the machine to measure loads of up to 1,000,000 pounds.
The machine is still held in working order at the Kirkaldy Museum in Southwark, although problems can occur with the gasket which seals the single hydraulic cylinder. This machine still uses the original material leather rather than a more modern material. Historically the water supply would have come form the London Hydraulic Power Company but now the museum uses an electric pump. When breaking specimens for visitor demonstrations a load not excceding 20 tons would be used.
He also developed methods for examining the microstructure of metals using optical microscopy. It involved cutting sections, polishing the sections and then etching to reveal different constituents.
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. Some were reused in local houses, and when they were demolished in the 1960s, some were removed to the Royal Museum of Scotland in Edinburgh, where they are on public display.