Ergonomic Grocery Bag Holder

thingiverse

This is a rework for the awesome grocery bag holder designed by ivanseidel. I made it a bit more form-fitting to the user's hand and also more low-profile. I think it feels great, and can easily handle a decent amount of weight. Just for fun, I wanted to run a (VERY) basic FEA simulation comparison between the two models. This was based on solid ABS and 35 lbf static load distributed across three handles (I read some comments in the original post saying that it failed at this weight, though I don't know the failure mode or location). It looks like the new model with solid ABS has a 3.2 safety factor, which occurs in an incorrectly calculated stress concentration area. This is compared to 2.9 safety factor on the original design (located at the base of the middle hook). It can be hypothesized that this could have been the failure that other users experienced. I originally left extra material here in my rework only as a leftover from the design, though it appears that it actually adds decent structure to the design and may increase its lifespan in the long run. There is also a stress concentration on the outer edges of the handle, which looks significantly higher than the stress in the center hook. I thought that by adding material to the center hook might drive more stress to the outer edges of the handle, but by simulation comparison this doesn't seem to be the case. I'd love to hear others' thoughts on this as well as the rework in general. Thanks again to ivanseidel for inspiring this design!