Testing a Neck Strap

Yep. Since you said "prove", you're gonna need to do some type of statistical test. I don't know enough about your application to even guess which. Perhaps some type of CHI Squared? Find a decent statistician and show him what you want to do.

A quick and simple test is to get a bunch of friends and get them to wear the harnesses under different conditions. Their feedback should give you a good indication.

Actual tests and conditions will depend on what the neck strap/shoulder harness is actually supporting and the expected environment it is to be used in.

I was trying to do a test that was more scientific than just surveying people on how comfortable they think it is. Is there any way to measure weight distribution? i figured the more comfortable strap would distribute weight more evenly.

How comfortable people think it is may be WAY more important than weight data. Statistics can be compiled on each, however.

Sure. Put load cells in the straps.

When I was working in the headset field, long story, and we wanted to compare comfort levels, we sat a group of people down and had them wear the things.

Nobody is exactly alike, in so many ways, that you cannot objectively determine what will feel good to them.

After you have chosen the winner, you can then employ many means to duplicate the desirable properties.

^{_{What's the matter, No friends? You've been working too much!}}

Cheers.

When testing neck straps, always remember to:

1. test them on friends first;

2. don't leave them hanging too long. The friends, that is.

Cheers!
DZ

Mike seen your question on my LinkedIn wall, and had the following reply below ...

Mike Webster

Mutiple load cells mounted in stratigic locations. Math in PLC?
Omega.com, search Products for load cells.
Mike

If this is what you mean by a 'neck strap' (see pics), then basically your Load = Force / Area (of neck strap)

so if you were to place 50 lbs at the lower ends, tied together, then this load is applied across the top half of the strap. The vertical portions, or more specifically, portions which do not have frictive contact with the wearer, are not included in the equation.

You could divide up the applicable portion of the strap which does bear the load into a finite number of segments, and do some calculus thing... because the load applied to each angled element is going to be different... As the load varies with each angled element, so does its angle, and therefore, the greater the angle, the less load it carries. I'm sure there are a number of ways to calculate this but...

what you will see is that the as the angle reduces, so does the "Apparent Width" of each element, as viewed from the top. What I think you can assume is that the load applied is proportional to the apparent width. This gives you the simple fact that the sum of the apparent element widths is equal to the area for the applied load, so you simply have to measure the apparent width, multiply that times the strap width, to get your necessary area for the equation.

For example, if the apparent width is 8", and the strap is 1" wide, then the area is 8 square inches. The equation would be 50 lbs divided by 8 sq in, which would give a value of 6.25 lbs/sq/in.

As you adjust your strap width, or place it in different locations, you now have a method of comparison.

Hope that makes sense.

Chris

ISOMETRIC VIEW OF STRAP ELEMENTS

TOP VIEW

The way I see it is:.... To you a wider strap might seem more comfortable ...to another person the narrow strap might feel better to them.........I would think your attempt to PROVE anything here is impossilble.

I have a question. How come a cushioned strap is more comfortable then say, just a plain old strap that is the same width. What is the physics behind this? Both straps would be holding the same weight on your neck.

A cushioned strap won't cut into your neck, and it will mould itself into your neck better giving a greater spread of the load. Just guessing. Sit on a wooden chair, then sit on the same chair with a cushion - seemingly the same contact area, but not. Your bum hasn't got bigger, but it's more comfy. Also, if you rock (sideways)slightly the lifted buttock is still getting some support if a cushion is used.