# Designing an Impact Force Testing Device

• Roscoe48176
In summary, the conversation discusses the creation of a testing device to produce a specific impact force on an electrical device. The design includes a steel plate being dropped onto a steel base plate at a specific height and weight. However, the calculation of the necessary weight is not possible without further testing and experimentation with accelerometers. It is suggested to contact a company, Bruel & Kjaer, for assistance in obtaining the necessary equipment for this experiment.
Roscoe48176

## Homework Statement

I am creating a device to provide 250 to 300 g's of impact force to an electrical device in a plastic housing. I would like to lift a steel plate approximately 16" x 16" X thickness "T",, to a height of "Y" and release it. It would fall at the rate of gravity, impacting a steel base plate and come to rest. The goal is to determine the weight of the plate based on it's thickness and set the height required to create the desired impact force of 250-300 g's. The test must be able to be repeated with consistent results. I have designed the tool, but lack the information requested above.

F=Ma ?

## The Attempt at a Solution

I am not a physics student,, I am a product designer trying to test the impact forces placed on a device. Thank you.

You can't work it out from that.
You can calculate how much energy/momentum a falling block will apply quite easily but to know what force it will apply to the object you need to know how quickly the block will stop - which depends on how the test object will deform.

It's a bit like dropping something on the floor, the same mass dropped on a concrete floor will experience much greater shock than one dropped on wood - becuase the wood deflects to slow the object down over a longer time and so has less accelearation.

mgb_phys,,

The base plate of the testing device will be 16" x 16" x 2" thick steel plate. The device will rest on a concrete floor to run the test. 4, 1/2" diameter steel rods will be mounted into the base plate and slide through the mounting plate to guide the mounting plate up and down.

Is there anything else I can provide to assist you?

There is no practical way to calculate this - without doing CFD modelling of the part and for such a high force over a short time this wouldn't be remotely accurate.
The problem is that G force will peak over a very short time - it doesn't take a very big change in the design to give you 100g for 2.5us rather than 300g for 1us.

The best I can suggest is to get some accelerometers, attach them to the plate and experiment with the peak shock - this has got a lot easier since fast digital storage scopes were invented!

thanks for your help,,, I'll work on it from that angle

Call Bruel & Kjaer. Ask for a sales engineer to drop by. They'll sell you what you need.

## 1. What is the purpose of designing an impact force testing device?

The purpose of designing an impact force testing device is to measure the amount of force exerted on an object during an impact. This information is crucial in understanding the potential damage or injury caused by an impact and can be used to improve product design and safety.

## 2. What factors should be considered when designing an impact force testing device?

Some important factors to consider when designing an impact force testing device include the type of impact (e.g. drop, collision), the weight and size of the test object, the required precision and accuracy of the measurements, and the safety precautions for both the operator and the test subject.

## 3. How does an impact force testing device work?

An impact force testing device typically consists of a platform or surface for the test object to rest on, a way to apply the impact force (such as a drop tower or pendulum), and sensors to measure the force and acceleration during the impact. The data collected from these sensors is then analyzed to determine the impact force.

## 4. What materials are commonly used in the construction of impact force testing devices?

The materials used in the construction of impact force testing devices can vary depending on the specific design and purpose of the device. However, some common materials include metals such as steel or aluminum for the frame and support structures, and various types of sensors and transducers for measuring the force and acceleration.

## 5. How can the results from an impact force testing device be interpreted and applied?

The results from an impact force testing device can be used to evaluate the safety and durability of a product or structure, as well as inform design improvements. They can also be compared to industry standards and regulations to ensure compliance. Additionally, the data can be used in simulations and modeling to predict the effects of impacts in different scenarios.

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