I was going through some old work and thought I would update some of my programs in a recent version of Microsoft Visual Studio. Old dogs and new tricks so to speak, but Visual C# is sufficiently similar to Visual C++ so it wasn't too bad. One of those was a program to fit curve parameters. The routine and the results are shown below the break. I will be making the executable file available on the Google Drive in the Downloads area in the very near future.
One major use for explosives is in the oil and gas industry to complete a well. For a simple well the process is straightforward. The well is drilled, cased and then perforated. This involves inserting a length of tubing with a series of shaped charges along it's length into the cased well and setting off the charges that perforate the casing and the oil and gas bearing strata.
A shaped charge in its simplest form is nothing more than a metal cone surrounded by explosives. The charge is end initiated and the explosive collapses the conical liner into a jet of material that penetrates at very high velocity. The jet penetrates in the same manner as I previously posted about hypervelocity penetration. A model of a simple 65 degree angled shaped charge is shown in the first video. As the detonation proceeds up the charge the cone collapses inward in a symmetrical manner with an upwards momentum. At the collision point the cone coalesces into a jet of material that has a high velocity and has a final form of a long slender rod.
Energetic materials in general and explosives in particular are incredibly important to an industrial/technological society. For propellants it's their ability to produce large volumes of gas in a short time frame during combustion. Rocket motors put our satellites in space that provide us with other forms of important technology. The airbags in your car are nothing more than an energetic material undergoing rapid combustion to fill the bag. I don't think you want to know what energetic material is probably in there.
The usefulness of explosives comes from the fast generation of gas, on the microsecond timeframe or less, that provides a large power density and amount of work available. This allows us to do extensive momentum transfers for a relatively low cost (blasting for mining and construction). The metals production industry, and subsequent manufacturing industries heavily depend on the low cost production of raw materials. The power densities in explosives allow for the high velocity acceleration of metals which produces the shaped charge effects needed in oil and gas well completion.
From the first post in this series I wrote about determining the performance of an explosive using the Cylinder Expansion test, or Cylex as it's commonly known. As I mentioned the radial velocity of an expanding cylinder (copper for the cylex test) is measured. This is done a number of different ways. The earliest method used a streak camera.
This is the first part of a series on the properties and application of explosive materials. I suppose the first thing to do is define some terms. An explosive is any system, gas, liquid, or solid, that will propagate a supersonic wave front at a characteristic velocity that is supported by chemical reaction. A graphical relationship helps to show this.
Much of my work over the years involved testing and developing explosive systems. What I hope to do with this series of posts is to describe in a succinct form some of the background, both theoretical and experimental, that went into my work. This series of posts is an overview of explosive materials and their uses. It's similar to some texts available but I will be including links and various downloadable items that some readers might find useful.
There are three basic types of explosive materials: primaries like azides and fulminates; secondaries such as HMX, RDX, and TNT; commercial, which include variants of ammonium nitrate/fuel oil used in the mining industry.
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