As consumers of endless products, we can more or less trust that if it is on the market, it is safe for us to use. As long as we see that stamp of approval by each region’s certifying entity, we can freely go on to use that product fear-free. Behind this vote of confidence, there has been rigorous testing and certification. The modern consumer does not only want products that come with some guarantee of its value, but we also want the assurance that the whole process of its creation was done responsibly. This 21st-century consumerism does not only make sure we are safe, but that no living creature suffered to help it materialize. This is true for cosmetics that now carry the cruelty free stamp as well as for clothing that qualifies as fair trade. While we leave it in the expert hands of others to make our cars, coffee makers, sport watches and so on, we keep a watchful eye on how it is done. Bold Valuable Tech is on board with minimizing our carbon footprint while developing new and exhilarating technology – be it battery packs or lightweight structures.
The pre-simulation era
Before the advent of simulation testing, testing was a costly process of trial and error. It wasted manpower, time and the physical resources. It left many events to chance. With likes of the advanced technology Bold designs today, there used to be so many factors that had to be isolated one by one to thoroughly guarantee the precision and safety of the final solution. For example, recreating the thermal stress of the parts we develop could have even been a risky endeavor. This required controlled environments of vast dimensions that are power draining to recreate the thresholds the part would eventually endure. One could even say that an unwanted occurrence during this lengthy process was that creativity and innovation were terribly stifled.
Taking advantage of modern testing
The virtual environment is now at our fingertips to test concepts on any level we wish to program. The three most typical environmental stresses are temperature, humidity and vibration. Other environmental stresses that may be less prevalent in power electrics testing are altitude and corrosion. All of these situations can be simulated to an extreme with the tools Bold handles with dexterity. Apart from appeasing the uprise of responsible consumerism, the benefits obtained by companies include:
- Cost saving on materials and manpower
- Reduction of carbon footprint through less overseas shipping and handling
- Greater volume of productivity
- Greater control and localization of the solutions’ assembly
Bold’s team have dedicated senior engineers that can perform the studies required for batteries and structural component projects. For this, we consistently deliver high-quality solutions while cutting back on the unnecessary costs of yore.
The structural analysis we use Hypermesh with optistruct software. This state of the art software can simulate anisotropic materials, which is required for studying composite structures. Furthermore, it includes adequate failure criteria (Hill Tsai, Tsai-Wu, and Hashin) for post-processing analysis matrix and fibers of individual plies.
Additionally, we can study bolted and bonded joints. This most likely includes laminates with inserts of different materials (the most common being CFRP from flat stock, Aluminum 7075 and Titanium 6Al4V).
These tools will often highlight highly stressed areas that need to be addressed by the designer of the component. Ultimately, it is a combination of stress analysis, detail design and manufacturing process that will determine the outcome of the structure for a particular load case. In critical structures, a physical proof stress test is also highly recommended.
Battery thermal simulation
The thermal performance of a battery is a critical aspect of its performance. As a rule of thumb, lithium-ion cells do not like to operate beyond 60°C. Beyond that, there will be high damage to the chemical elements and materials inside the cell. Initially this will result in capacity and power fading, and ultimately to total damage and catastrophic failure.
Cooling systems are dimensioned to keep cells in the appropriate operating range to minimize power clipping. This means, the power of the cell is electronically limited, so the cell does not exceed the maximum allowed temperature. In order to obtain more performance, a more powerful cooling cycle is required. Another important aspect to take into account is the uniformity of cell temperatures around the pack. As cells are very sensible to temperature, the hottest or coldest cell will limit the entire power available for the rest of the cells.
Multiple iterations are required to develop the cooling system for a battery pack. Even with large amounts of data from previous designs, there is no one-size-fits-all solution. Each pack is different. Simulation software offer the possibility to test and iterate a design numerous before a pack is ready to be manufactured as a prototype. Bold uses Simscale and Altair CFD for battery simulation. In parallel to that there is always the need to test prototypes and correlate the analytical results with experimental data.
In-house testing with DC computerized loads and cooling system rigs offer the chance to quickly test the simulated solutions in a laboratory environment. Instrumented prototype packs provide the temperature, voltage and power readings to feed data back to the computer for design validation. This is a cost effective and simple solution to test in-house designs before making the initial investment for a large battery pack.
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