How can vibration shaker testing technology help manufacturers to optimise their battery designs?
Vibration testing of electric vehicle (EV) batteries during prototype development is vital for product validation, but can be expensive and time consuming.
During their long life, batteries and their subsystems, such as connections, cooling, etc., are susceptible to failures that can range from a decrease in battery performance to complete failure. Since batteries for electric and hybrid vehicles exist in a wide range of sizes, shapes, weights and chemical compositions, different test methods are critical to verify durability.
Vibration testing
For those involved in vehicle and battery manufacturing, optimising their designs and shortening time-to-market can be greatly improved by using vibration shaker testing technology, such the LDS V9940 shaker platform, which has been created specifically for vibration and shock testing on EV battery modules and packs, e-axles and e-drivetrains.
Designed primarily for testing EV battery systems during the initial development stage, to validate product release to series production, the V9940 shaker system can also be used for end-of-line sample testing to validate manufacturing process parameters and ensure consistency of quality for vehicle and battery manufacturers, independent Test Houses and Systems Integrators
It’s a water-cooled electrodynamic shaker with a Sine force rating of 300 kN, provides capacity for large payloads of up to 5000 kg (11,000 lb) for testing with sinusoidal, random, and transient excitations.
Designing the v9940
The design includes optimised table designs using innovative pedestal assemblies to minimise moving masses, greatly improving performance. Pedestal bearings are used to support the test load of large EV assemblies – instead of a full-size slip plate or head expander, thus reducing moving masses for particular payload orientation. The minimised moving masses create higher resonance and improved dynamics, meaning a lower force is required to achieve a specific test. Paired journal guide bearings are employed for displacement in the excitation axis, which allow for thermal expansion of EV batteries.
The related parts of the control systems are designed so that they comply with Safety Performance Level PL=d with structure category 2 as described in ISO 13849-1:2015, but it is worth noting that the installation will need to include interlocked gated access to the identified danger zones around each system.
Climatic chambers ensure that the test environments such as this accurately simulate real-world environmental conditions during battery tests, while providing important safety functions such as isolation and containment in case of thermal runaway.
Communication with climatic chamber and with a higher-level automation systems is possible with programmed digital I/O signals from the vibration controller. Thermal management options enable the user control over humidity, high pressure water spray/mist and flooding. These features ensure the performance of the system is maintained even in the event of thermal runaways, thus protecting the health and safety of test employees - and facilities.
Thermal barriers can be used on slip plates, head expanders and pedestals provide low thermal conductivity, very high compressive strength and resistance to electrolytes, water-glycol coolant, gear box oils & gases (H2, Ch4, CO, C.O2, C2H4, C2H6, etc.). Hot and cold units are used for tempering the slip plate and oil in preparation for environmental stress testing.
Tim Gardiner is the Product manager – VTS at Hottinger Brüel & Kjær (HBK)
