Shakers find wider applications

Modern medium range shaker systems are finding wider applications across different industries as development times fall

With a long history of use in stress testing and reliability modelling, industrial shakers have grown in their use across different industries to become an invaluable development tool used at all stages of product development, prototyping, testing and manufacture.

Within the large range of vibration test systems available, the LDS V8800 from Hottinger Brüel & Kjær (HBK) is a medium sized shaker that is finding broad application across multiple industries for its ability to handle medium sized payloads and have the flexibility to perform quiet mode testing and shock testing. To find out more about the LDS V8800 and its capabilities, we spoke with Tim Gardiner of HBK.

The LDS V8800 Shaker

HBK’s LDS V8800 is an air-cooled shaker system that can be used for vibration as well as mechanical shock testing with sinusoidal, random and transient excitation capabilities. It can take payloads of up to 700 kg and has a peak sine force rating of 59 kN and a maximum shock force of up to 175 kN.

According to Gardiner, the V8800 can be seen as a workhorse covering many applications across a number of industries and is used for testing electronics or avionics for example and can be used for testing against compliance to standards.

“It’s used in a research and development capacity as part of a drive to reduce development cycle times too, particularly in aerospace, defence and the automotive industries,” he says.

He explains that shakers of this size and payload rating are very versatile and can be used for components, sub-assemblies and even full assemblies for nano-satellites for example.

There isn’t a single shaker that can be used for everything. There are larger water-cooled systems that can take payloads of up to 5000kg for bigger assemblies but the mainstay of industrial component and sub-assembly work is taken by medium sized shakers.

Automotive NVH Testing

The automotive industry is a key user of the V8800, which is ideal for performing Noise, Vibration and Harshness (NVH) testing as well as battery testing at cell, module and even pack level.

“Noise vibration and harshness is a very key application for these shakers as is battery testing with strong demand from car manufacturers, who are developing these products in a very short amount of time,” says Gardiner.

NVH is an interesting variant on traditional vibration testing as it not only looks at structural response to input excitation but also examines the effect of vibration input on the occupants of the vehicle. This kind of testing includes BSR (Buzz, Squeak and Rattle) analysis to ensure automotive interiors remain durable and free of annoying noises. To this end, measurement takes place using sound sensors as well as the usual accelerometers to understand the overall response of the device under test.

One reason why the V8800 is particularly suitable to NVH testing is its “Cool” and “Quiet” mode capabilities.

Cool and Quiet are two energy consumption modes, which can easily be controlled via the amplifier’s user interface. The Cool mode automatically adjusts system settings to reduce the power consumption required for a test while the Quiet mode operates the shaker without a fan at low power to reduce noise.

NVH testing users therefore have the advantages of automated energy saving as well as reduced noise so that more accurate response measurements can be taken.

The NVH testing simulates between 250,000 and 300,000km of driving and I asked Gardiner whether the associated input profiles for such use cases were supplied by HBK or defined by their clients.

“We have a lot of experience of producing vibration profiles for many applications but its largely the customers who define what they’d like to cover in the testing. Nonetheless, we have a highly experienced special projects team, which can provide guidance and support where it’s needed,” he says.

Battery Testing

Electric Vehicle (EV) battery testing is also very relevant to the capabilities of the V8800 due in part to its ability to perform transient tests, such as shock testing for crash performance. Gardiner explains that the ability for battery packs to withstand the shocks associated with a crash are an important factor in assessing the vehicle’s crashworthiness.

Some traditional shakers don’t perform well in these kinds of transient tests without needing to use a matching transformer to deliver the extra power. However, the 88kVA XPA-K amplifier on the V8800 delivers the necessary breadth of power needed for shock testing without the need for a matching transformer.

The V8800 is able to meet the shock test requirements of battery cells and modules as well as smaller sized battery packs.

Supplied as standard with an air-isolation trunion with a body rotation gearbox, the shaker can be connected to an optional slip table as part of an easy upgrade in order to enable full operation in X, Y and Z planes. This allows horizontal shock testing to be performed on battery products.

The XPA-K amplifier and optional slip table as well as guided and unguided head expanders provide an extremely versatile combination to allow the full range of medium payload shock and vibration testing capabilities for EV development and testing.

Climatic Chambers

Increasingly in the automotive and space industries, there’s a need to combine vibration testing with climatic testing and so the V8800 can be base mounted for under-chamber operation.

The shaker system is compatible with environmental testing equipment, including AGREE chambers.

“Particular care and attention has to be given to make sure that the interface between shaker and chamber is very efficient, we want to make sure that the DUT is well within the climatic chamber so that it’s getting the full effect of the environmental conditions,” says Gardiner.

It isn’t just about positioning and control though as there are additional safety considerations to be taken into account with battery testing. As batteries can experience thermal runaway events in extreme conditions, extinguishing functions, such as flooding the test chamber, need to be considered.

Monitoring for Maintenance

The XPA-K system has in-built monitoring capabilities to continuously check the status of the shaker. This data is stored for both analysis and also to support preventive maintenance and fault detection. It is also accessible to system users in real-time via the amplifier’s touch screen.

Monitoring through HBK’s servers is also offered alongside service contracts whereby the
XPA-K amplifier can be connected to an HBK VPN server so that the company’s team can help with fault detection and diagnostics.

According to Gardiner, as an example HBK can use the data to extrapolate when there could be a failure with the goal being to do any necessary work within the planned maintenance schedule to prevent the failure.

“For a lot of our customers, up-time is absolutely key so we’re very committed to supplying these services to make sure the machines are up and running as much as possible,” he says.

Improved up-time is also built into the device by virtue of its innovative inductive centring system, which maintains the correct position of the armature during operating, a crucial element of successful vibration testing.

Vibration tables typically use optical technology to achieve this but has the disadvantage of being prone to environmental factors such as dust, heat etc. As a result, they need to be maintained and calibrated.

By contrast, the V8800 shaker’s Inductive Centring System (ICS) is immune to such conditions. This not only eliminates the need for regular calibration and sensor maintenance, but also increases the reliability, efficiency and uptime of the system.