9/20/2018 Wood Pallets and Unit Load Design: An International Expansion Welcome Message Ingredients don’t bake themselves into a cake. Only the application of wisdom and ingenuity can deliver something of greater value than the components. Kristen DeLack, PE Structural Engineer National Wooden Pallet page & Container Association 02 1 9/20/2018 There are billions of pallets in service, supporting international trade. Outline • Introduction • Languages • Wood and Nails • International Species • Connection Strength • Storage & Handling • Transportation • Unit Load Design • System Level View • Optimization • Question & Answers 2 9/20/2018 Questions for You 1. International Species a) What international species classes are you interested in? b) Can you help donate material for or sponsor testing? c) Can you provide regulatory body or industry sponsored mechanical property data? 2. What design challenges do you have? International Expansion National Wooden Pallet page & Container Association 06 3 9/20/2018 Multiple Languages may be needed National Wooden Pallet page & Container Association 07 Wood & Nails International Species Storage & Handling Connection Design Transportation National Wooden Pallet page & Container Association 08 4 9/20/2018 International Species A wide variety of hardwood and softwood species is used in pallet construction. Mechanical properties vary between species and growing region. Two ways to test properties: • Full size pallet components • Small clear samples National Wooden Pallet page & Container Association 09 International Central and South American European Species Classes Species Classes Species Classes Prioria Copaifera Imported Hardwoods Radiata Pine Mengkulang Oceanian Species Classes (Chile) Kapur Radiata Pine Gmelina Arborea Keruing (Australia) (Costa Rica) Dense European Hardwoods Maritime Pine, Pinus Pinaster Pinus Caribaea Ash: European (Australia) (Venezuela) Beech: European Radiata Pine Pinus Elliottii Oak: European (New Zealand) (Brazil) Plane: European Pinus Taeda Dense European Softwoods (Brazil) Douglas-fir Eucalyptus Grandis Larch: European, Japanese SE Asian Species Classes (Uruguay) Pine: Maritime, Scots, Jack Anisoptera Ponderosa Pine Medium Dense Woods (Malaysia) (Mexico) Poplar: Grey, Black Italian Anisoptera Pinus Patula Elm: Dutch (Philippines) (Mexico) Redwood Shorea Ocote Pine Fir: Silver (Philippines) (Mexico) Larch: Hybrid Dryobalanops Pine: Lodgepole, Corsican Fir: Silver African Species Classes Whitewood Pinus Patula Elm: English East Asian Species Classes (Madagascar) Spruce: Sitka (Canada) Sugi, Japanese Cedar, Crtomeria Melina Wood, Gmelina Arborea Whitewood japonica (Japan) (Nigeria) Japanese Larch, Lariz Kaempferi Pinus Patula Common European Softwoods (Lmab/) Carriere (Japan) (S. Africa, Mpumalanga & KZN) Pine: Radiata Maritime Pine, Pinus Pinaster Spruce: Black, Norway (S. Africa, Mpumalanga & KZN) Willow: White National Wooden Pallet Pinus Patula Spruce: White, Sitka (U.K., Eire) page (Tanzania) Hybrid Poplar & Container Association Black Alder, Alnus Glutinosa 010 5 9/20/2018 Testing Full scale pallet components UK/Ireland: • Scots pine • British spruce Australia: • Radiata Pine National Wooden Pallet page & Container Association 011 Storage & Handling Connection Strength Fastener Properties Stiffness Strength • Fastener withdrawal • Head Pull Through • Lateral strength National Wooden Pallet page & Container Association 012 6 9/20/2018 Fastener Properties National Wooden Pallet page & Container Association 013 Nail Bending Strength MIBANT: Morgan Impact Bend Angle Nail Test National Wooden Pallet page & Container Association 014 7 9/20/2018 Joint stiffness Moderately important Stiff Connection Lower stress in board Lower deflection Flexible Connection Higher stress in board Higher deflection National Wooden Pallet page & Container Association 015 Connection Strength – Perimeter base block pallet example Nails RAL Safe Load Deflection @ 1000 lbs Critical Member 2 1085 lbs 0.53” Butted Board to Block (Lateral) 3 1494 lbs 0.48” Center Top Stringerboard 4 1477 lbs 0.46” Center Top Stringerboard 38% additional capacity by adding six nails National Wooden Pallet page & Container Association 016 8 9/20/2018 Connection Strength – Fork tine support example 3 2 Fork Tine Tip Supporting Lifting Safe Load Critical Member 3rd board 2175 lb TD Interiorbd to Stringer (Withdrawal) 2nd board 3381 lb Interior Top Deckboard 2nd board (poor fastener) 1909 lb TD Interiorbd to Stringer (Withdrawal) National Wooden Pallet 55%+ additional capacity by providing better support page & Container Association and avoiding very poor nails 017 Forklifting From Side of Stringer Pallets • Tested over 200 simulated forklift notches • No degradation due to presence of notch corners was observed • Compression damage opposite the fork tine occurred before break • Lifting capacity from the side of stringer pallets can be much higher than from the end • Included in PDS 5.6 National Wooden Pallet page & Container Association 018 9 9/20/2018 Lateral Collapse Loss of stability subjected to transportation accelerations Qualitative Analysis Transit Analysis National Wooden Pallet page & Container Association 019 Lateral Collapse • Fully updated lateral collapse model • Capable of providing an estimate for acceleration limit for pallets only restrained at the bottom deck Acceleration Acceleration acting Acceleration acting Mode of transport acting forwards backwards sideways Road vehicle 1.0 g 0.5 g 0.5 g Railway Subject to shunting 4.0 g 4.0 g 0.5 g Combined (intermodal) transport 1.0 g 1.0 g 0.5 g Sea Baltic sea 0.3 g 0.3 g (b) 0.5 g North sea 0.3 g 0.3 g (c) 0.7 g Unrestricted 0.4 g 0.4 g (d) 0.8 g National Wooden Pallet page & Container Association 020 10 9/20/2018 Lateral Collapse Analysis General (Default) Output Transit G-force Analysis National Wooden Pallet page & Container Association User Specified Load 021 Unit Load Design Applied Research Pallet Design & Analysis Product Differentiation Checklist Design for requirements Manufacturability Box Design & Analysis What Materials? Substitutions? Design optimization Efficient use of materials Lifecycle cost Analysis vs. testing… Drawings, datasheet, analysis results National Wooden Pallet page & Container Association 022 11 9/20/2018 Stretch Wrap National Wooden Pallet page & Container Association 023 Box Crush Testing • Over 400 boxes of varying sizes and materials have been tested • Effects of high humidity were investigated • Testing determines stiffness and failure characteristics of each box used in the analytical model National Wooden Pallet page & Container Association 024 12 9/20/2018 Unit Load Research –Block Pallet Testing page Laboratory grade block pallets for testing 025 Full Scale testing National Wooden Pallet page & Container Association 026 13 9/20/2018 Stringer Pallet Unit Load Testing Racked Across Width Analytical Model Laboratory Test National Wooden Pallet page & Container Association 027 Load Sharing During Racking Across Width A portion of the load is carried by the boxes National Wooden Pallet and a portion is supported by the pallet page & Container Association 028 14 9/20/2018 Racked Across Length, Medium Boxes, Peri. Base Block Pallet Box Compression Stress Pallet Designs Tested 40% increase in box stress for B0 – Extremely Flexible RAL with half B1 – 0.375” top deck as thick boards boards, 0.5” elsewhere B2 – 0.5” boards B3 – 0.625” boards B4 – 0.75” boards B5 – 0.5” boards, unidirectional base Higher stress under 2nd pallet due to missing boards page 029 Critical Box Compression page 030 15 9/20/2018 Racked Across Length, Medium boxes Pallet Stress Big reduction in stress page 031 Questions & Answers 16 9/20/2018 Thank You. Fredells Travaru AB Super Global 17.