Epoxy strength test

[Kevin Johnson]

https://youtu.be/R3r0UZ7txzs

[Walter R. Malik]

https://youtu.be/R3r0UZ7txzs

I have done some tests of my own and when the temp gets above 300 degrees F, epoxies differentiate themselves quickly.
So, be sure to also know the temperature ranges of the different epoxies you are going to use.

[Rick!]

I'm not sure what structural adhesive characteristics were really tested in that video.
The thread pull out test could be construed as a shear strength test.
The one heat resistant mixture has impressive numbers but you could see that its continuous heat temp was just above half of its "ultimate" temp.

When I designed structural adhesive joints, creating a shear joint was absolutely critical as that is the mat prop of adhesives that is meaningful.
I've had some joint designs that could separate powder coat from e-coat when doing pull tests.
If one designs an a structural bond that is put in peel, the bond strength is considerably reduced. Joints in peel (tensile loading) are not suited for bonding.
Most MMAs and epoxies aren't happy above 250F unless they are specially formulated.
The guy didn't use any Master Bond epoxies as they are considerably more expensive. That would have been interesting to see the shear results of the proper adhesive.

Gotta give the guy kudos for at least doing 3 samples of the thread shear test.

A 5/16" bolt and nut is an easier and cheaper fix for the broken chain, assuming it didn't hit you in the back of the head when it broke.
A hose clamp over the top of the pipe plug would have generated higher pressure numbers. At least he submerged the samples when pressurizing them but he still couldn't locate all the failed plug parts. Shoulda used a deeper tank.

[j-c-c]

I agree on your 3 "shear" sample test compliment to the author, but I would have liked to see a compilation percentage of the total spread of the 3 "shear" tests, which I guess I could do myself, but I think knowing the potential variation is useful. Is a thread pull out test a proper shear test, or would a typical lap adhesive joint pull test be a better test?

[Rick!]

I always created double lap shear joints for lab tests.
Sometimes the adhesive joints were stronger than the material of the single coupon end so thicker coupons were used.
Single lap shear joints deflect non-uniformly and the results were far too inconsistent.
I believe we used ASTM D3528 for testing guidance for load application.

[Kevin Johnson]

https://civilengineersstandard.com/wp-c ... D-3528.pdf

[Dan Timberlake]

I'm thinking pitting a "filled" epoxy against epoxy resin ain't fair at all, except for simply gluing sh*t together.

Compressing pucks and yanking out threaded fasteners would seem to bring the filler into play on two or 3 levels.

[Kevin Johnson]

https://www.youtube.com/results?search_ ... poxy+tests


https://www.youtube.com/results?search_ ... poxy+tests

[j-c-c]

I always created double lap shear joints for lab tests.
Sometimes the adhesive joints were stronger than the material of the single coupon end so thicker coupons were used.
Single lap shear joints deflect non-uniformly and the results were far too inconsistent.
I believe we used ASTM D3528 for testing guidance for load application.

I understand that double shear may test the adhesive more accurately, but in our real world use double shear adhesive joints are a rarity? So maybe both should be tested, or test a larger number of samples to get a realistic average?

[Dan Timberlake]

The U-tube tests I looked at are well intentioned.
Some of the ones that stick the head of long bolts to a bar, and then apply weights at the cantilevered end of the bolt lack consistency in the botl head/bar interface. Specifically, building up a healthy sized fillet around the bolt head is far different than a pure face-to-face bond job.

[Rick!]

The "test" of gluing the SHCS to a bar are utter bs. Nobody does that in the engineering world.
Epoxy and MMA are use in purposely designed shear joints and never in peel.
All you have to do is go up a few videos and watch the Master Bond one where they describe the adhesives and give all the important properties of them. You'll note that peel is the weakest strength of these adhesives.
Where I used to work, we developed "tube in socket" joints that would yield thin wall seamless 4130 before the adhesive failed.
Anyway, I guess watching folks making up stupid glue tests on Youtube is at best, entertaining.

[Kevin Johnson]

...
Anyway, I guess watching folks making up stupid glue tests on Youtube is at best, entertaining.

I would venture that most people that buy and use these commercially packaged products are not engineers. For better or worse the videos likely portray real-world use by the public.

[Truckedup]

A few years before I retied as a construction electrician epoxies were being used to replace mechanical anchors . Mostly for securing threaded studs in poured concrete structures. Sometimes they worked, sometimes not. A famous failure was in the Boston underground roadway project where large panels fell off the ceiling when the epoxy failed. The engineers blamed the workmen. The workmen blamed the engineers that thought what works in a lab situation would work in a dusty filthy dimly lit actual work site.

[Kevin Johnson]

I think it is great that middle and high school students are learning to design experiments, collect data and analyze results.

I trust that they will receive further instruction in research methods, particularly centering around stating an unambiguous null hypothesis (i.e. more care in disputing a claim with the verbiage of "up to") as well as inadvertently introducing experimental confounds in an attempt to avoid them ("batch effect" i.e. using three different tubes and (presumably) generating a P-Value that does not separate out which failure values are associated with a particular tube. Random assignation does not really apply here.).

Samantha says to me that "you're a downer" and "poor kids."

Cover photo for Testing Epoxy Strength: The High Strength Claims of Selleys’s Araldite Epoxy Glues
Epoxy resin is a type of thermosetting polymer that is considered among the best matrix materials with excellent properties including high flexibility, good dielectrics, chemical inertness, and water repellency. The strength of epoxy can be influenced by crosslinked density and the incorporation of a variety of solid particles of butadiene. It is important to understand the techniques used to improve the adhesion strength of the epoxy resin, especially for consumer applications such as repairing car parts, bonding aluminum sheeting, and repairing furniture or applications within the aviation or civil industry. Selleys is a well-known Australian company specializing in cleaning products, adhesives and sealants; their Araldite epoxy makes specific strength claims emphasizing that the load or weight that can be supported by the adhesive is 72 kg/cm2. Our experiment aimed to test the strength claims of Selley’s Araldite Epoxy by gluing two steel adhesion surfaces: a steel tube and bracket. Altogether, a 55 mm surface was used, meaning the load held by the brackets would be 41.25 kg. Loads were added to the bracket as a destructive tensile load test were conducted. To avoid batch effect, three tubes of Selleys’s Araldite epoxy were used. Our results showed that there was a significant difference between actual load and the expected load (41.25 kg) (a two-tailed t-test with p -value < 0.05 with a fracture stress ranging from 0.019 MPa-0.095 MPa, disputing the claim that Selleys’s Araldite epoxy can hold up to 72 kg/cm2 a s we expected the p -value to be > 0.05 in order to accept the claim. The experiment showed that there is a lack of consideration by Selleys for adhesion loss mechanisms and environmental factors when accounting for consumer use of the product leading to disputable claims.
reference
https://infotainmentbeats.com/
https://www.emerginginvestigators.org/a ... poxy-glues