Hypothesis:

I think out of the three fasteners, the screw will do the best in all tests because it becomes embedded in the material, making it strong. Its metal material and thickness also helps with its strength and unlike a nail, it has some grooves to secure it into the wood whether we pull or create moment on it. These factors help it resist forces better and lift more weight than the other two.

Prediction:

If I compare screws to nails and glue, I think the screws will carry the most amount of weight before crumbling, followed by nails, and lastly the glue.

 

 

• If forces are equal they cancel out/resist each other to be neutral (equilibrium)
• A moment = a torque or turn caused by a force acting on an object. The moment acts on the axis or a fixed point of the object
• The force wants to turn (moment force) the diving board causing it to bend
• Stronger forces or longer lengths can increase moment force
• Moment force = force x moment arm length (if force is perpendicular to object and if newtons use meters and if pounds use inches)
• Tension force = stretching and pulling of a material (on two opposite sides) by pulling the molecules they want to push back. Tension along the area of tensile is equal to each other
• The largest amount of that force an object can take would be called a “force” strength
•  
• Joint = Where parts of a structure are joined (with)
• Fastener = The material sealing the joint
• Restoration Force = When an object is stressed, it produces an equal restoration force to counter and help it not collapse. This force keeps it from damage, unless the load/force is so big that the restoration force can’t cancel it out, then it breaks or bends/gets damaged
• Spring Force = When the object asserts a force to bounce the object back to its original shape 
• Load = the weight a structure carries 
• Direction = the direction the force hits at
• Magnitude = the amount of force that hits
• Normal Force = When 2 surfaces are in contact, they exert a normal force which is perpendicular to the surface to make sure the surface doesn't go through it. It is written as N with an arrow on top.
• Axial Force = a force that is in the direction of the axis of the body

Controlled: 

• How the test was executed (machines & forces)
• The material used (spruce wood) 

Dependent: 

• How well it handled the load
• When it broke
• How much it strained
• The load it carried (KG)

Independent: 

• Type of joint
• Type of test

Materials:

• Nails
• Screws
• Wood (we got spruce)
• Glue (wood glue)
• Weights (plates) (KG)
• Clamp
• String
• Saw 
• Nailgun
• Screwdriver
• Measuring stick (inches)
• Table
• Wall that can be clamped (We used the side of a table

Procedure:

Building Of Our Joint Structure

1. Get your wood, saw and fasteners
2. Cut 2 pieces of wood, one at 5 inches, the second at 7 inches
3. Layer on top of each other to create a 90 degree angle (make sure the 5 inch piece is on top of the 7 inch one)
4. Connect the ends with the fastener (for screws and nails drill/hammer, and for glue apply, clamp and wait to dry)
5. Repeat for each joint 4 times

Moment Test

1. Secure the 5 inch piece to a table using a clamp. Make sure the clamp is holding the top of the 5 inch piece
2. Make sure the 5 inch piece is parallel to the wall/flat surface. 7 inch piece is exposed and not supported by anything directly underneath
3. 3. On the part sticking out (the 7 inch piece) add weight to it

4. 4. Hold each weight for 10 seconds before taking it off, and repeat with heavier weights until the joint breaks

   5. Record results or observations

   Tension Test

5. Find the part that is vertically attached to the wood
6. Loop a rope through the rings of the weights
7. Attach both sides of the rope on that part through a clamp. Put the string 75% of the 7 inch wood and clamp half way
8. Add weight, repeat process and see when the joint separates 
9. Make sure you test each weight for 10 seconds
10. Record observations and results

Nails

#1

2 lbs= sagged down, permanently

1.5 KG= sagged down a lot (wobbly), permanently

2 KG= sagged a lot, nails exposed (114 degrees)

2.5 KG= sagged down too much, broke

#2

2 lbs= sagged slightly (around 2 mm) 91 degrees 

1.25 KG= sagged a lot, permanently, 92 degrees

1.5KG= sagged a lot, nails exposed, 95 degrees

2 KG= broke sagged too much, 125 degrees

#3

2 lbs= sagged, 93.5 degrees

1.25 KG= sagged a lot, permanently, 113 degrees

1.5 KG=broke, 131 degrees

Screw

#1

2 lbs= strong, no sign of weakness

1.25- 2 KG= slight down (less than mm), strong

2.5 KG- 2.75 KG- 3 KG=slight sag (around 2 mm), 90 degrees

3.5 KG= slight sag (around 2.5 mm), wobbling, 90 degrees

4 KG=sagged a lot screw exposed 113 degrees

4.5 KG= broke, 115 degrees

#2

1.25 KG=slight down/wiggle, 90 degrees

1.5- 2 KG= slight down, 90 degrees

2.5 KG= slight down (around 1.5 mm), 90 degrees 

3 KG=sagged, around 2 mm, 90 degrees

3.5 KG= sagged quite a bit, 90 degrees

4 KG=broke, twisted, screw exposed, 110 degrees

#3 (this one had pre-existing crack in wood, so disqualified from actual results)

2 lbs= sagged slightly

1.25 KG=sagged 91 degrees

1.5 KG= sagged quite a bit (1.5cm), 91 degrees

2 KG= sagged a lot 91 degrees

2.5 KG=sagged a lot, wiggly(1.9 cm), 92.5 degrees

3 KG= sagged even more, more wiggly (2.2 cm), 94 degrees

3.5 KG= Cracked, noise, screw split wood

Wood Glue

#1

1.25, 1.5, 2, 2.5, 2.75, 3.25 KG= strong, no sign of weakness, rock solid

3.5 KG= see some tense (less than mm sag), strong

3.75 KG=strong

4 KG= same as 3.5

4.5 KG= slightly more sag than 4, strong

5-5.5 KG= good

6 KG= strong

7 KG= strong, clamp struggling 

8 KG= strong

9 KG= strong

10 KG= strong

12 KG= broke, stood well then suddenly snapped and fell

#2 

2-7 KG= strong, slight down less than a mm

8 KG=slight down (heard noise, ta)

9 KG= strong

9.5,10,10.5=slight down

11 KG= same as previous, but heard noise

11.5 KG= same as previous but louder noise

12, 12.5 KG= slight down

13 KG= as soon as 13 came (plate 5/6), snapped 

#3

2,2.5,3 KG= strong, no sign of weakness

5 KG= some sound (stress)

5.5 KG= some osund, slight down less tham mm

6 KG= same as 5 KG

7 Kg= strong, little signs, less than mm down

8, 9 KG=slight noise, strong

9.5 KG= strong, slight down

10 KG= same as 9 KG

10.5 KG= snapped

 

What Moment Test did:

In short it:

• Tested moment and ability to produce restoration and spring force
• Wood acted as lever to split wood making it harder to hold
• Tested at an angle (90 degrees) which is practical and used in furniture
• Replicated the diving board example with the joint being the fixed point
•  
• Failure of the tension test

• One test I had tested the joints durability when it comes to the tension force, but it failed. Here is why it failed and what we learned

  Why It Failed:

• The clamp that was holding the string was slipping due to the amount of weight on the string (12 KG)
• All the joints managed to hold the max load, with the glue and screw barely showing any signs, meaning the test didn’t find the limits (therefore ineffective)

• What I Could've Done Differently:

• I could’ve used something other than a clamp, maybe a hook that was drilled in the wood 
• Still learned that these joint’s axial force strength is greater than their normal force strength

• Observations and what it tells about the fastener

  Joint Fastener	Nails	Wood Glue	Screw
  Observations	Nails bent a lot and didn’t go back to normal In tension, nails started to slide off When tested one nail did the same weight as 2  Area of both nails = 0.06cm²	Very strong, until collapsed suddenly Area of glue = 79.36 cm²	Sagged slightly, but always came back to original 90 degrees Area of the screw = 0.44178cm²
  What it Meant	It could not produce a restoration force to hold it and could not produce a spring force  The nails experienced a bending force Probably would have failed tension test first There isn’t a lot of difference between one or 2 nails	It produced a strong restoration force and spring force, but when overpowered, snapped with no signs of weakness Covered whole surface	It had a decent restoration force and a good spring force Since the nails also did, the screw probably experienced a bending force, but it could withstand it

   

• Wood glue strongest, taking the crown 
• Hypothesis wrong as I thought screws would do the best and glue did the best

Factors To Wood Glue Success:

1. Covered whole surface in layer: This meant the force very evenly spread out and performed better than the nails and screw needing to cover a vast area. This created a strong layer that each little glue carried a little of the total load (79.36cm2 vs 0.06 cm2 of both screws amd 0.44cm2 of the screw)
2. It didn’t rely on the Material Durability: It had a layer that meant it was independent. This was useful in this test as wood was soft spruce. We see how this affected the nails and screws by how the faulty screw structure that had a crack, stood less then the ones with no crack in the wood (3.5 KG vs 4 and 4.5 KG) and how in the tension test, the wood got indented slightly
3. That layer resisted from the lever: Wood at end was levering each other, the screws and nails had to withstand amplified force from this, while glue had a layer to resist the wood turning into a lever, possibly why when it suddenly collapsed, the load was too heavy, and when the glue weakened and the lever formed, the force amplified and instantly snapped the glue

   Why Screws Weren’t The Best:

   The Good:

4. Was thick: We saw unlike the nails, it didn’t bend much. This was due to its thickness giving it some more durability. This resisted from the force better than the nails
5. Grooves secured it: The grooves helped it stay secure. In the failed tension test we saw the nails starting to come off, but the screws remained strong. The grooves helped with this, securing it in the wood giving strength especially in the axial forces

6. The Bad:

7. Reliant on weaker material: In this situation we used soft spruce wood, which isn’t the most strong. The screws relied on the material durability evidence by how in the 3rd attempt of the moment test when it had a pre-existing crack, it lifted less than the other to attempts (3.5 KG vs 4 KG and 4.5 KG). This took it’s strengths and turned into weaknesses, like in that third attempt the screw broke through the material, probably because of its grooves cutting the wood open.
8. Had a lever: As the screws cut through the wood, it formed a lever which amplified the force and assisting the screw break through by adding the wood pressuring down on the screws grooves while the screw was already pushing up (shear force)
9. Turning its strengths into weaknesses, was the main point why it wasn’t the best, perhaps it would’ve done better if we tested a stronger type of wood

10. Why Nails Did Bad:

11. Friction didn’t save it: Usually, nails work around the idea friction keeps it in, but in this we tested it when it was on its side in the moment test. This means the friction part did little to nothing it the moment test. 
12. Were thin metal: Nails are flat thin metal. This means other than friction there were nothing securing it and the thin metal had little to non restoration or spring force. This is evident by how it always bent without any restoration force and remained in that in the tests.
13. Very vulnerable to lever: We saw the nails bend a lot and the wood edges touching. This meant the lever formed and it was vulnerable due to the other factors. This created an amplified moment force on it, greatly impacting its low performance

• Furniture: We tested 90 degree joints which are the joints in furniture. This experiment can help us with creating stronger furniture, so furniture doesn't break or wobble as easily. 
• Strength: In architecture and design, we need strength so stuff doesn't get damaged and joints play a huge role in a structure’s stability. This experiment will help us find out which joint can provide the most strength so structures don’t fail as much

• Humidity and temperature of environment (though can’t change results too much)
• Weight combination: with many plates, could have been inconsistent on what weight combinations to a specific amount of KG. Eg. 2+2+2+2= 8, but so does 2.5+2.5+1.5+1.5 and I forgot to track the specific weight combinationso possible this happened but can only affect high ammounts of weights that only wood glue accomplished

Sources:

• https://pressbooks.library.upei.ca/statics/front-matter/introduction/
• https://www.passtheare.com/joints-in-architecture-understanding-the-terminology-and-differences-for-are-5-0
• https://architecturedfrobichaux.com/joints-construction-buildings
• https://www.teachengineering.org/lessons/view/wpi_lesson_1#:~:text=The%20five%20types%20of%20loads,%2C%20shear%2C%20bending%20and%20torsion.
• https://mrdenney.weebly.com/uploads/1/3/7/6/13767597/lesson_10.4-_external_and_internal_forces.pdf
• https://www.youtube.com/watch?v=xPFRRh-lWxM
• https://www.ksb.com/en-global/centrifugal-pump-lexicon/article/axial-force-1117062
• https://www.youtube.com/watch?v=Hn_iozUo9m4https://www.youtube.com/watch?v=Hn_iozUo9m4
• https://www.khanacademy.org/science/mechanics-essentials/xafb2c8d81b6e70e3:could-a-coin-dropped-from-a-tall-building-kill-you/xafb2c8d81b6e70e3:why-do-you-feel-heavier-in-a-lift-when-it-starts-moving-up/a/what-is-normal-force
• https://languages.oup.com/google-dictionary-en
• Images in Background research from newit.org and https://physicsican.blogspot.com/2019/07/moment-of-force.html