Sensor solutions for increased seismic safety

For more than 60 years, IABG, a European technology company headquartered near Munich, Germany, has been carrying out safety tests with a focus on analysis, simulation, testing and plant operation. The company has been using acceleration sensors from ASC since 2011, which are specially adapted to the needs of the business.

ASC accelerators powering diverse test rigs

"Our core task is the evaluation of the functional safety and stability of components for energy production and newly developed high-tech products," explains Arbo Simon, Team Lead Vibration Tests and Earthquake Simulation at IABG’s Test Facility Operations Center of Excellence. Therefore, through its German and international branches, IABG provides technical and scientific services for private and public customers from sectors including automotive, mobility and energy, aerospace as well as communication technology, defense and security.

"The technical quality and diverse range of ASC’s sensors, as well as the company's great flexibility allow them to explore new avenues with us and to tailor solutions specifically for our innovative test benches."

Low-noise density for seismic accuracy

"Across our test rigs, we analyze the impact of acceleration forces from less than 1 m/s² continuous vibration load all the way up to 2,000 m/s² peak acceleration," says the expert. "These high-precision sensors register dynamic (AC) and constant, static accelerations (DC) and thus operate from nearly 0 Hz, which is particularly important for our seismological vibration tests, as the loads usually start at less than 1 Hz," the expert explains.

The triaxial capacitive low-noise (LN) accelerometers of the ASC 5711LN series, which are specially configured to meet the needs of the various applications at IABG, have a very low noise density even in high measuring ranges of +/- 200 g. In combination with the MEMS-based sensors’ excellent response behavior, this leads to feasible resolutions of only a few millionths of gravity (µg).

Californian earthquake certification standard

How reliable is a building, system or product in the event of an earthquake? Vibration tests reveal this. At the accredited multi-axis (6 DOF) HyMAS (Heavy Multi-Axial Shaker) vibration test lab for earthquake simulation and fatigue strength testing of plant and building components weighing up to 14 tons, for example, around 80 percent of seismic tests carried out by IABG are for plant operators and product manufacturers, in order to provide experimental proof for the qualification of components in accordance with international earthquake standards. To effectively prevent technical failures in the event of an earthquake, well over 1,000 individual tests have been carried out for (nuclear) power plants, medical technology, energy companies, aviation, railway and the automotive industry. These included many generators, transformers, switch cabinets and other sensitive safety-related components of nuclear, wind and other types of power plants.

IABG is the only company in Europe that is listed with the California Department of Health Care Access and Information (HACAI) and authorized to carry out certification processes according to its rigorous criteria. "We evaluate for various magnitudes, durations and amplitudes of earthquakes," says Simon. Wind turbines, for example, are additionally exposed to six to eight hours of continuous vibrations caused by different wind forces.

Seismic vibration loads typically occur spatially distributed and randomly. As the test specimen must be evaluated according to its real installation and set-up position in order to obtain valid results, the experimental vibration test is conducted with simultaneous, multi-axis excitation. The HyMAS and LiMAS (Light Multi-Axial Shaker) test benches – a multi-axis vibration test bench with combined environmental simulation for accelerations up to 130 m/s2 and test specimens weighing up to 1,000 kg – therefore, enable spatial movement in all six degrees of freedom by means of differently arranged hydraulic cylinders.

Rapid response to customer needs

The customized accelerometers of the ASC 5711LN series are based on high-quality, micromechanical sensor elements that convince through long-term stability and reliability. The integrated electronics enable a differential, analog voltage output (±4 V signal deviation) and a flexible power supply from 6 to 40 VDC. ASC’s LN (low-noise) accelerometers are characterized by an excellent signal-to-noise ratio – a fundamental requirement for sophisticated measurements of low frequencies and amplitudes. They are, therefore, frequently used in structural health monitoring of sensitive structures such as tunnels, bridges, dams, power stations and other buildings where the smallest tectonic vibrations could have dramatic consequences.

"Given our high demand and tight turnaround times, it helps enormously if our partners can react flexibly and quickly. For example, ASC was recently able to implement a new cable requirement without any issues. Furthermore, the easy handling and installation of ASC’s sensors, their lightweight but robust housing, their flexible use across our various test benches and the DKD calibration are decisive advantages for us."