# Measuring impact force on rubber spacers

• Hank P
In summary, the spacers are distributed over the shell, and are supposed to dampen any external impact loads to reduce the effective stress inside the inner shell. However, the FEA model is not showing results, so the author attempted to do the calculations by hand. The impact load and stress at the inner shell would be enough to calculate, but the author cannot figure out how to account for the distribution of the spacers.

#### Hank P

I need to find the impact force that can be absorbed by these spacers as shown in the image. The spacers are radially distributed over the shell, and they are supposed to dampen any external impact loads to reduce the effective stress inside the inner shell. Since the FEA model is not showing results, I thought of attempting it by hand to get an approximate value. A curve relating the impact load and stress at the inner shell would be enough.

However, I cannot figure out how to account for the distribution of these spacers, since depending on the load some of these will be in tension, compression and/or shear. The shell is polycarbonate and the spacers are silicon rubber.

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Why would you need to know the impact force that can be absorbed?
Surely you just need to know that the spacers can take a prescribed maximum impact?
In which case you need only measure for impact with only one.

Note: it is not the sort of thing you calculate: drop it on something hard (or drop something hard on it) with an accelerometer inside.
That sounds drastic I know - to et an idea of what to expect, you set up a test rig to work out how each spacer behaves.

The overall impact profile will be very complicated - the thingy may initially strike 1, or 2, or 3 at once - probably just one at a glancing blow - then would bounce and roll, maybe also deforming, to bring other spacers in contact. There is no what to predict the exact results.

You could model specific impact profiles by treating the device as two spheres separated by damped springs.

This doesn't help with the question, but I'm curious: How does it work with the 2 intermediate shells? Do the spacers just go through holes in them, or are they also attached?

Thanks Simon. I guess I'll keep trying and see if the simulation works. Can't set up an experiment where I work. I could just do this with a single spacer, but a spherical surface helps distribute the forces all over, so my calculation would just be an approximation for a flat surface.

Danger, The spacers have cones with flats on both ends, which mate with flats on the shells.

Hank P said:
anger, The spacers have cones with flats on both ends, which mate with flats on the shells.
Okay, I think that I can sort of see that now. Thanks.

## 1. How do you measure the impact force on rubber spacers?

The impact force on rubber spacers can be measured using a force sensor or load cell. The sensor is placed between the object causing the impact and the rubber spacer. When the impact occurs, the sensor measures the force applied, which can then be recorded and analyzed.

## 2. What factors affect the impact force on rubber spacers?

The impact force on rubber spacers can be affected by several factors, such as the speed and weight of the object causing the impact, the material and thickness of the rubber spacer, and the surface on which the impact occurs. Other factors, such as temperature and humidity, can also have an impact on the force measurement.

## 3. How accurate are the measurements of impact force on rubber spacers?

The accuracy of the measurements depends on the quality and calibration of the force sensor used. With a properly calibrated sensor, the measurements can be very accurate, with a margin of error of less than 1%. However, external factors such as vibrations or improper placement of the sensor can affect the accuracy of the measurements.

## 4. What is the unit of measurement for impact force on rubber spacers?

The unit of measurement for impact force is typically Newtons (N) or pounds (lbs), depending on the system of measurement used. Some force sensors may also provide measurements in kilograms (kg) or grams (g).

## 5. How can the data from measuring impact force on rubber spacers be used?

The data from measuring impact force on rubber spacers can be used to analyze the effectiveness and durability of the rubber spacer in various situations. It can also be used to compare different materials or designs of rubber spacers, and to make improvements or adjustments to optimize their performance. Additionally, the data can be used for research and development in industries that use rubber spacers, such as automotive or aerospace engineering.