Well, they're in New Mexico; I doubt they'd appreciate being associated with Texas.
SwRI is in San Antonio, Texas. That's considered Central Texas by Texans, not West Texas. And yes, Texas is big enough for those distinctions to matter. San Antonio is not in the region of the United States considered the Southwest. But if "Northwestern" University can be in Illinois, then what's in a name?
You may be misled by the client address. Gregg Bemis lived in New Mexico. He was famous as the owner of the
RMS Lusitania wreck, about which he also had certain suspicions.
Bemis submitted for analysis two metal samples from
MS Estonia's forward bulkhead, the area behind the visor. Bemis alleged them to be "structural" components, despite their being only quarter-inch steel. (Bemis was not an engineer.) The report summary indicates the lab was to look for evidence of shock loading "such as might result from detonation." No loaded questions there! The lab summarily dismissed one sample as displaying no evidence consistent with shock loading. The other sample was inconclusive. We're waiting for our resident Triple-Niner to give us the benefit of that high-octane intelligence in properly interpreting the report.
In the inconclusive sample, the lab noted "twinning," a particular arrangement of steel microstructure. It also noted a relative lack of "necking," the thinning of ductile materials before fracture when the material is bent or stretched relatively slowly. Twinning can be caused by a number of things including fatigue induced by cyclical loading (i.e., when stress is applied and released repeatedly). Non-ductile fracture may occur under cryogenic temperatures (< -150 ºC) and/or under high strain rates (when material bends or stretches rapidly so that it doesn't have time to "neck"). There is no smoking gun.
The lab was unable to determine which of those occurred because the necessary telltales had been obliterated by corrosion. The lab offered to develop a different test methodology for an additional fee. We can reasonably rule out cryogenic temperature. It's quite reasonable to believe the bulkhead material was subject to cyclical loading due to its proximity to the visor and ramp structures—which were obviously repeatedly cycled during the ship's normal operation—and its location in the ship's shell plating layout, which would have been subject to cyclical loading from wave action. Quarter-inch steel is more consistent with shell plating than with structural components on a ship.
High strain rates can occur in a number of situations, including those caused in ship breakups. The failure of structure such that gravity loads pass suddenly to shell plating is such an example. A Mode III shear fracture can progress transversely across the material thickness. Or it can progress parallel to the fracture line, in which case it becomes a "running" shear fracture. Both kinds can exhibit high strain rates, but a detonation shock load will necessarily be in the transverse direction because the load is applied uniformly against the face of the material. A running shear fracture is far more common and is characteristic of overstress fractures, such as when the material is simply pulled apart quickly by being asked suddenly to bear too much load. That loading is not uniform, but rather concentrated on the fracture tip. In the running case the fracture tip fails under load; in a detonation there is effectively no fracture tip but rather a fracture edge.
In uncorroded materials, microscopic examination of the fracture edge would determine the direction of progression. Here the lab could not make that examination because the edges were corroded. Hence the lab carefully framed its findings by saying, "If cryogenic temperatures and running shear fracture can be ruled out, these could be considered evidence of shock loading." Or, translated into Triple-Niner, "If you can rule out the more common and ordinary causes, then you might be able to consider explosives."
In looking at all these reports, it's going to be important to either know or accurately guess what question the lab was asked to answer. Otherwise honest and disinterested people like poor Prof. Amdahl can be roped into supporting pseudoscience simply by being asked loaded questions. "What kind of ship would need to hit
Estonia in order to cause such a hole?" obviates the task of determining whether it was
any kind of ship at all. Similarly, asking a lab, "Could this kind of damage be caused by an explosion?" sidesteps the question of whether that's the best or most evident explanation for the damage. It's asking about the possibility of one explanation irrespective of any others, rather than asking what the best explanation is.
Finding evidence of shock loading "such as might result from detonation" doesn't ask for a differential diagnosis. It's like asking a coroner specifically whether a victim's laceration might have been caused by an ancient Sumerian ceremonial dagger. Well, yes, that's certainly a possibility given the generally ambiguous nature of lacerations. But if the victim was known to have been in a car crash, the laceration might best be explained by torn metal or shards of broken glass, not the exotic reason called out in the brief. Here SwRI has hinted at the right answer without violating its remit: If you have other reasons to eliminate the obvious, prosaic causes for what's observed in the metal then you might have reason to believe there were explosives involved.
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