Electro Servo Motors or Linear Motors for Shake Tables: Choosing the Right Technology

In the realm of shake tables, used predominantly for vibration testing and simulations, two main types of electric motors come into play: servo motors and linear motors. A servo motor is a rotary actuator that allows for precise control of angular position, velocity, and acceleration. It consists of a suitable motor coupled to a sensor for position feedback. Servo motors are well-suited to a wide range of automation applications.

On the other hand, linear motors stand out due to their ability to directly convert electrical energy into linear motion without requiring any intermediate conversion from rotational motion. This direct-drive mechanism results in a plethora of advantages, particularly for shake tables which demand high fidelity and precision.

Linear motors are heralded as the most advanced technology in shake table systems due to their exceptional performance characteristics:

  1. Unmatched Acceleration and Velocity: With their direct-drive design, linear motors achieve unparalleled acceleration and velocity, surpassing that of servo motors. This capability is crucial for tests necessitating rapid motion or high-frequency vibrations.
  2. Minimal Maintenance Demands: The design of linear motors inherently involves fewer moving components compared to servo motors, translating to reduced maintenance needs and an extended operational lifespan.
  3. Quieter, Smoother Operation: Linear motors operate with significantly less noise and vibration. This is especially advantageous for tests where external noise or vibration could contaminate results.
  4. Supreme Precision and Accuracy: The precision control afforded by linear motors is essential for high-precision testing scenarios, offering superior repeatability and accuracy over servo motors.
  5. Enhanced Energy Efficiency: By eliminating the need for gearboxes and other mechanical components, linear motors are not only less complex but also more energy-efficient, reducing energy loss during operation.

Despite these advantages, there are considerations to keep in mind when opting for linear motors, such as initial costs, installation complexity, and the typically lower torque capabilities relative to servo motors. However, when advanced technology and performance are paramount, the investment in linear motors can be justified.

At the forefront of this technological revolution is QuakeLogic, which proudly offers state-of-the-art ironcore shake tables powered by linear motors. These tables represent the zenith of testing precision and reliability. A testament to their superiority, QuakeLogic’s latest installation at CALTECH underscores the confidence that leading research institutions place in linear motor technology for their complex and critical testing needs.

For detailed information on the iron-core shake table equipped with linear motors, please click HERE.

Reach us at sales@quakelogic.net for questions or queries.

Unveiling the Seismic Shadows: Which District of Istanbul Will Shake the Most?

Istanbul, straddling two continents, is not just a city of unparalleled historical and cultural wealth but also one that lives in the shadow of a significant seismic threat. The North Anatolian Fault (NAF), a major source of earthquakes in the region, skirts to the south and east of this vibrant metropolis, placing it at a heightened risk of seismic activity. But in a city so vast, the question arises: which district of Istanbul will bear the brunt of such an inevitable shake?

The sequence of westerly propagating ten large (M>6.7) earthquakes on the North Anatolian Fault Zone and the seismic gap in the Sea of Marmara close to Istanbul is an indication of a large earthquake.

The Epicenter of Concern: The Riskiest Districts

Historical data and seismic studies indicate that the districts closest to the North Anatolian Fault zone beneath the Marmara Sea, especially those on the city’s European side, are more vulnerable. Our most recent study (Kalkan and Gulkan, 2024) indicates that Istanbul’s western shoreline faces heightened risk, with median spectral accelerations at 0.3 s approaching 1 g, signifying intense shaking potential. Among these, Adalar, Bakırköy, Avcılar, and Zeytinburnu stand out as areas that might experience the most intense shaking. These districts, with their dense populations and structures, many of which were built before modern seismic standards were implemented, could face significant impacts in the event of a major earthquake.

The figure above shows close-up to peak ground acceleration (PGA) estimates for the Istanbul metropolitan area considering six earthquake scenarios. The median computed PGA­­ is 0.65 g along the shoreline to the west of Istanbul (Bakırkoy district) and at Marmara Islands (Adalar district) as a result of multiple rupturing of Off-Tekirdağ, Mid-Marmara, and Islands faults.

The Science of Shaking: Understanding the Risk

Seismic risk is not only about proximity to the fault line but also about the ground beneath. Areas built on softer, sedimentary layers, such as parts of Avcilar, Atakoy, and Bakırköy amplify seismic waves, leading to more intense shaking compared to those on more solid rock. This geological variability across Istanbul means that the impact of an earthquake can differ dramatically, even within short distances.

Preparedness: The Key to Resilience

While the threat is significant, the focus now is on resilience and preparedness. Istanbul’s government and various organizations are working tirelessly to retrofit vulnerable buildings, improve emergency response systems, and educate the public about earthquake preparedness. Efforts are particularly concentrated in the high-risk districts, aiming to minimize the impact when the inevitable occurs.

Conclusion: A City Bracing for Its Future

As Istanbul faces its seismic future, understanding the areas at greatest risk is crucial for safeguarding its residents and heritage. While many districts along its shoreline may be more vulnerable, city-wide efforts to enhance resilience are a testament to Istanbul’s determination to protect its people and preserve its legacy against the forces of nature.

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Are you from Istanbul or have experiences related to earthquakes in the city? Reach us at info@quakelogic.net

Understanding the Earthquake Shaking: The Modified Mercalli Intensity Scale (MMI)

When the earth trembles, the world takes notice. But how do we measure the narrative of the ground’s fierce rumbling? Enter the Modified Mercalli Intensity Scale (MMI), a storyteller of seismic experience that narrates the drama from the ground up.

Intensity vs. Magnitude: Feeling the Difference

While magnitude scales like Richter or moment magnitude measure the energy released at the earthquake’s source, the MMI scale offers a human-centered narrative. It tells us what people felt, what damage occurred, and how the landscape changed. This scale isn’t just about numbers; it’s about experiences.

The Scale of Stories

From I, where the shaking is not felt except by a select few under favorable conditions, to XII, where damage is total, structures are uprooted, and the earth’s surface is wrenched, the MMI scale plots the plot points of an earthquake’s impact. Each level up the scale marks a significant increase in the effects felt and damage inflicted.

Click HERE to download the MMI scale in PDF.

Local Tales of a Global Phenomenon

What makes the MMI scale particularly useful is its adaptability to various settings. The same earthquake can be gentle in one location and destructive in another. By cataloging responses from different areas, seismologists can map out an earthquake’s impact in a way that resonates with the local narrative.

A Chronicle of Resilience

Beyond its scientific value, the MMI scale is a record of resilience. It highlights how communities withstand the shaking, adapt to their transformed landscape, and rebuild in the aftermath. It’s a human scale for a natural event.

In the end, the Modified Mercalli Intensity Scale does more than tell us how the Earth moved. It connects us through shared experiences and mutual understanding. It’s a reminder that while we may be separated by geography, we are united in our encounter with the natural world.

When the earth shakes again, as it inevitably will, we will turn to the MMI scale not just for data, but for the stories of survival, strength, and solidarity. It is a scale that does not just measure shakes, but also stirs the human spirit.

Stay Grounded with Knowledge

Understanding the MMI scale can help us better prepare for future seismic events. By learning from past earthquakes, we can build structures and communities that are not only earthquake-resistant but also resilient in the face of whatever the MMI scale may tell us next.

For comments and suggestions, reach us at info@quakelogic.net