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Boat trailure winch bolt failure

Don Blanchet
Don Blanchet

a lot of bolts were received with an incorrect certificate of compliance , field failures were numerous

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Boat Trailer winch main bolt failure FEA damage analysis Solidworks Simulation 2019 3/30/2019 rev B Don Blanchet 3B Associates dwb3298@outlook.com Prepared for: National Boat Certification Association Washington, DC
Solidworks 2019 model Main bolt 遜 inch
Failure summary A production lot of winches exhibited a very high rate of warranty claims for failures of the main bolt. Upon examination the failed bolts all came from the same purchase lot from an off-shore vendor. Metallurgical tests revealed that the bolts did not meet the winch manufacturers specs.
Purchase order specified SAE grade 5 bolts strength 120,000 psi Testing of the lot of received bolts revealed an average Strength of less than 50,000 psi Winches had been assembled and inspected using a Certificate of Compliance from the off-shore vendor.
Qualification test proof loading performed once a year no lot testing Design proof load = 6000lb Maximum recommended use load = 3000lb FIXED BASE
Max calculated distortion under a 6000 lb load = .014 inches Solidworks FEA simulation 2019 STATIC LOADING
Max calculated bolt stress with 6000 lb load = 58,000 psi BOLT FAILURE PREDICTED FOR 50,000 PSI BOLT MATERIAL STRENGTH
Max calculated bolt stress with 6000 lb load = 58,000 psi BOLT SAFE FOR the SPECIFIED 120,000 PSI GRADE 5 BOLT MATERIAL STRENGTH Factor of safety 120,000/58,000= 2.1
Analysis Summary 6000 lb design Load Resulting peak Stress psi Strength psi Factor Of Safety Low Strength Bolt 58,000 50,000 0.86 High Strength Bolt 58,000 120,000 2.01
Conclusion - recommendations The bolt material certificate of compliance was not correct or fraudulent. Remove the vendor from the Qualified Parts List. Demand recertification or change vendor. Perform a recall to cover liability.

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Boat trailure winch bolt failure

  • 1. Boat Trailer winch main bolt failure FEA damage analysis Solidworks Simulation 2019 3/30/2019 rev B Don Blanchet 3B Associates dwb3298@outlook.com Prepared for: National Boat Certification Association Washington, DC
  • 3. Failure summary A production lot of winches exhibited a very high rate of warranty claims for failures of the main bolt. Upon examination the failed bolts all came from the same purchase lot from an off-shore vendor. Metallurgical tests revealed that the bolts did not meet the winch manufacturers specs.
  • 4. Purchase order specified SAE grade 5 bolts strength 120,000 psi Testing of the lot of received bolts revealed an average Strength of less than 50,000 psi Winches had been assembled and inspected using a Certificate of Compliance from the off-shore vendor.
  • 5. Qualification test proof loading performed once a year no lot testing Design proof load = 6000lb Maximum recommended use load = 3000lb FIXED BASE
  • 6. Max calculated distortion under a 6000 lb load = .014 inches Solidworks FEA simulation 2019 STATIC LOADING
  • 7. Max calculated bolt stress with 6000 lb load = 58,000 psi BOLT FAILURE PREDICTED FOR 50,000 PSI BOLT MATERIAL STRENGTH
  • 8. Max calculated bolt stress with 6000 lb load = 58,000 psi BOLT SAFE FOR the SPECIFIED 120,000 PSI GRADE 5 BOLT MATERIAL STRENGTH Factor of safety 120,000/58,000= 2.1
  • 10. Conclusion - recommendations The bolt material certificate of compliance was not correct or fraudulent. Remove the vendor from the Qualified Parts List. Demand recertification or change vendor. Perform a recall to cover liability.