Compression or Tensile on Fiberglass

[n707jt]

Homework Statement

A piece of aluminum as shown in the picture is applying a compressive force on the fiberglass material. I need to know if the loading material will exceed the specification of the fiberglass material.

Homework Equations

Properties of fiberglass
Tensile strength Monolayer (Warp): 380 MPa
Tensile strength Monolayer (Weft): 300 MPa

Fiber Volume: 50%

Properties of resin
Tensile strength: 30 MPa

Volume: 50%

The Attempt at a Solution

My question is, since the loading structure is pressing against the fiberglass, the load will cause the fiberglass to be stretched inwards thus resulting in tension. Is this deduction reasonable?

 

[PhanthomJay]

Is that an aluminum frame of sorts breing pressed upward against a fiberglass panel which is supported along its edges only? If so, the fiberglass bending streses are tensile on the outside fibers and compressive on the inside fibers, just like any plate subject to bending loads. Calculating those streses is quite difficult without a copy of Roarke's 'Stress and Strain' or computer finite element software.

 

[n707jt]

Hi there,

I do have Roark's. But I am not so sure if it possible to apply those formulas meant for metal plates to my composite? I am quite lost actually. :(

 

[n707jt]

Hi there,

I've included a picture of my loading condition. I've realized Roark does not provide any flat plate condition similar to that of my problem but I was wondering if it is possible to use Case no 8 in page 508 of Roark's?

I plan to take the outer dimension minus the inner dimension. Please advise as I am extremely new to structural engineering and I would gladly appreciate if someone could help me.

Thanks!

 

[DeeNos]

Yes, your deduction is reasonable. When a compressive force is applied to a material, it causes the material to experience tensile stresses internally. In the case of fiberglass, the loading material pressing against it will cause the fiberglass to stretch inwards, resulting in tension within the material. This tension must be taken into consideration when determining if the loading material will exceed the specifications of the fiberglass material. Additionally, the properties of the fiberglass and resin must also be considered, such as their respective tensile strengths and volume percentages. By comparing these properties, you can determine if the loading material will exceed the specifications of the fiberglass material.