Tensile Strength & Resin/Ash Burn Off Questions

Discussion in 'Fiberglass and Composite Boat Building' started by bucketlist, Aug 30, 2021.

  1. bucketlist
    Joined: Nov 2020
    Posts: 41
    Likes: 4, Points: 8
    Location: London Ontario

    bucketlist Junior Member

    Could anyone please steer me in the right direction to find resources on data for Ultimate Tensile Stress numbers and weight sample ( before /after burn off ) numbers/ percentages ?
    Is there a normal range for UTS in ksi for a fiberglass sample 6-7 mm thick , not cored , hand laid and polyester resin used ?
    Is there % ranges for Ash content for a coupon burn off ? How to tell if resin rich or resin shy ?
    Thank you in advance .
     
  2. Ad Hoc
    Joined: Oct 2008
    Posts: 7,079
    Likes: 1,011, Points: 113, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    Not such an 'easy' answer to that one. Since it, as always - depends.
    It depends upon the resin, the glass used, its direction, it is hand lay up or vacuum etc etc..and as such values can range from circa 100 MPa to 700MPa.
    Without knowing what the laminate schedule is, it is hard to say whether the values you have are representative of the values that are expected for that laminate schedule.
    As such those numbers are - well - just that, a series of numbers.
     
  3. bucketlist
    Joined: Nov 2020
    Posts: 41
    Likes: 4, Points: 8
    Location: London Ontario

    bucketlist Junior Member

    Thank you for the reply .
     
  4. rxcomposite
    Joined: Jan 2005
    Posts: 2,406
    Likes: 394, Points: 83, Legacy Rep: 1110
    Location: Philippines

    rxcomposite Senior Member

    Before you attempt to reverse engineer the properties of the laminate by testing samples and burn off test, familiarize yourself with the LR or ISO formula for predicting UTS of a laminate.

    Do not be intimidated by the equation as some are in easy to follow quadratic form. LR or ISO formula for UTS are close together and should not be a problem.

    The UTS formula are based on the MINIMUM properties of the material used (fiber and resin) and some hints or is specific on the compatibility of the "appropriate" resin to fiber use. The glass content/resin content ratio are also based the method of construction, that is Hand layup or Vacuum assisted. You may have to consult other books for approximate glass content achievable for different processes,

    Remember, the formulas prediction is based on MINIMUMS and as such, the resulting UTS is rather "conservative". To predict UTS with a specific resin and fiber in mind, there are other more complex method and complicated math plus a myriad of material properties required for the equation.
     
  5. fallguy
    Joined: Dec 2016
    Posts: 5,105
    Likes: 960, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    Report your data here and see what rx says can be inferred. It isn't going to throw him off.
     
  6. Mr Efficiency
    Joined: Oct 2010
    Posts: 10,293
    Likes: 995, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    You should have been able to pretty accurately assess what that laminate consisted of, by visual inspection, and attempting to prise it apart .
     
    rxcomposite likes this.

  7. rxcomposite
    Joined: Jan 2005
    Posts: 2,406
    Likes: 394, Points: 83, Legacy Rep: 1110
    Location: Philippines

    rxcomposite Senior Member

    For a start, what is the lamination schedule, the types of fabric used, and the resin used?
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.