What is Physical Simulation?

Physical Simulation of materials processing involves the exact reproduction of the thermal and mechanical processes in the laboratory that the material is subjected to in the actual fabrication or end use. A small sample of the actual material is used in the simulation. The material follows the same thermal and mechanical profile that it would in the full scale fabrication process or end use of the material. Depending on the capability of the machine performing the simulation, the results can be extremely useful. When the simulation is accurate, the results can be readily transferred from the laboratory to the full size production process.

DSI equipment can be used for the following applications:

Frequently at Dynamic Systems we are asked, "Why physical simulation? Isn't it just another name for physical testing?"

The short answer is no, they are not the same. While all physical simulation involves physical testing, the key difference is that physical simulation attempts to replicate real-world processes on a laboratory scale in a way that the resultant data can be used to solve real-world problems.

For example, it is fairly easy to heat a metallurgical specimen to a nominally uniform temperature in a furnace, then compress it to measure the deformation at a given temperature. This is a physical test, and when performed properly, it should yield reproducible results.

But if the investigator wants to achieve the microstructure and material properties derived from a process, or wants to model that process so as to gain a better understanding of the process or to improve the process, then a physical simulation of that process should be done.

As an example, if the investigator's goal in performing the test is to learn how to set up a rolling mill for a new alloy, then more information is required. Anyone who has ever observed steel being rolled will have noticed that the edges of the slab are darker than the middle of the slab, and the corners, where the edges meet, are darker still. That's because the edges and corners of the slab cool faster than its main body. As a result, the slab is not at a uniform temperature; instead, there are thermal gradients between warmer and cooler portions of the slab. Thermal gradients are present in every heating and cooling process and thus are part of almost every metal fabrication process. Research has clearly shown that thermal gradients affect ductility and thus the workability of material. The careful investigator, therefore, will have to physically simulate these thermal gradients (and other factors as well) in order to gather meaningful information in the laboratory that can later be applied successfully to the production rolling mill.

Frequently physical simulation must be performed in a series of steps: one test to simulate the corner of the slab, another to replicate part of the edge, another to replicate a portion further in. The data can then be linked together to form an accurate predictive model that can be used to set the operating parameters for the production rolling mill.

Here are some examples of how physical simulation is being applied today.

Optimizing Continuous Casters Through Physical Simulation

Lessons from the Japanese

The idea of using physical simulation to optimize a continuous caster is not just a theoretical concept; its practicality and value have already been demonstrated at a variety of steelmakers. Physical simulation on Gleeble systems played a major role in the first implementations of continuous casting at one of the largest steelmakers in Japan. During initial startup of the first continuous casters in volume production, cracks were developing in the steel as it was cast, making it necessary to remove nearly 50 percent of the steel surface to eliminate the cracks. A company researcher used a Gleeble system to physically simulate the casting process. Based on the results of his studies, he was able to suggest changes to the process. The caster was shut down and modifications to the caster and the operating parameters were made based on the physical simulation results. When the process was re-started, the surface of quality material increased to over 95 percent. The company was so impressed with the resultant cost savings and product improvements that it made similar changes to all the casters throughout its other steel mills.

Solving Processing Puzzles Through Physical Simulation

It's an exciting time in materials engineering. It seems that new materials appear almost every day. Some, like low-alloy carbon steels and exotic stainless steels, are new variations on a familiar theme. Others, such as aluminum lithium alloys, titanium aluminides, aluminum iron-cerium alloys, metal matrix composites, and powder metals, are less well understood materials destined for exotic applications. The challenge presented by each of these materials, whether familiar or exotic, is to find ways to produce and process them so they will function properly in their intended applications.