Wood Pallets and Unit Load Design: An International …...9/20/2018 1 Wood Pallets and Unit Load Design: An International Expansion National Wooden Pallet & Container Association Welcome

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Wood Pallets and Unit Load Design: An International Expansion

National Wooden Pallet & Container Association

WelcomeMessage

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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, PEStructural Engineer

9/20/2018

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There are billions of pallets in service, supporting international trade.

• Introduction• Languages• Wood and Nails

• International Species• Connection Strength

• Storage & Handling

• Transportation• Unit Load Design

• System Level View• Optimization

• Question & Answers

Outline

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1. International Speciesa) 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?

Questions for You


InternationalExpansion

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Multiple Languages may be needed

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Wood & Nails

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International Species

Storage & Handling Connection Design

Transportation

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InternationalSpecies

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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


InternationalSpecies Classes

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Central and South American Species Classes

European Species Classes

Prioria Copaifera Imported HardwoodsRadiata Pine Mengkulang

Oceanian Species Classes (Chile) KapurRadiata Pine Gmelina Arborea Keruing(Australia) (Costa Rica) Dense European HardwoodsMaritime Pine, Pinus Pinaster Pinus Caribaea Ash: European(Australia) (Venezuela) Beech: EuropeanRadiata Pine Pinus Elliottii Oak: European(New Zealand) (Brazil) Plane: European

Pinus Taeda Dense European Softwoods(Brazil) Douglas-firEucalyptus Grandis Larch: European, Japanese

SE Asian Species Classes (Uruguay) Pine: Maritime, Scots, JackAnisoptera Ponderosa Pine Medium Dense Woods(Malaysia) (Mexico) Poplar: Grey, Black ItalianAnisoptera Pinus Patula Elm: Dutch(Philippines) (Mexico) RedwoodShorea Ocote Pine Fir: Silver(Philippines) (Mexico) Larch: HybridDryobalanops Pine: Lodgepole, Corsican

Fir: SilverAfrican Species Classes WhitewoodPinus Patula Elm: English

East Asian Species Classes (Madagascar) Spruce: Sitka (Canada)Sugi, Japanese Cedar, Crtomeria japonica (Japan)

Melina Wood, Gmelina Arborea (Nigeria)

Whitewood

Japanese Larch, Lariz Kaempferi (Lmab/) Carriere (Japan) Pinus Patula Common European Softwoods

(S. Africa, Mpumalanga & KZN) Pine: RadiataMaritime Pine, Pinus Pinaster Spruce: Black, Norway(S. Africa, Mpumalanga & KZN) Willow: WhitePinus Patula Spruce: White, Sitka (U.K., Eire)(Tanzania) Hybrid Poplar

Black Alder, Alnus Glutinosa

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TestingFull scale pallet components

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UK/Ireland:• Scots pine• British spruce

Australia:• Radiata Pine


Storage & HandlingConnection Strength

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Fastener Properties

Stiffness

Strength• Fastener withdrawal• Head Pull Through• Lateral strength

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Fastener Properties

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Nail Bending Strength

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MIBANT: Morgan Impact Bend Angle Nail Test

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Joint stiffnessModerately important

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Stiff Connection

Flexible Connection

Higher stress in boardHigher deflection

Lower stress in boardLower deflection


Connection Strength – Perimeter base block pallet example

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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

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Connection Strength – Fork tine support example

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Fork Tine Tip Supporting Lifting Safe Load Critical Member

3rd board 2175 lb TD Interiorbd to Stringer (Withdrawal)

2nd board 3381 lb Interior Top Deckboard2nd board

(poor fastener) 1909 lb TD Interiorbd to Stringer (Withdrawal)

55%+ additional capacity by providing better support and avoiding very poor nails

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Forklifting From Side of Stringer Pallets

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• 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

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Lateral Collapse

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Loss of stability subjected to transportation accelerations

Qualitative Analysis

Transit Analysis


Lateral Collapse

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• Fully updated lateral collapse model

• Capable of providing an estimate for acceleration limit for pallets only restrained at the bottom deck

Mode of transport Acceleration acting forwards

Acceleration acting backwards

Acceleration acting sideways

Road vehicle 1.0 g 0.5 g 0.5 gRailwaySubject to shuntingCombined (intermodal) transport

4.0 g1.0 g

4.0 g1.0 g

0.5 g0.5 g

SeaBaltic seaNorth sea Unrestricted

0.3 g0.3 g0.4 g

0.3 g (b)0.3 g (c)0.4 g (d)

0.5 g0.7 g0.8 g

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Lateral Collapse Analysis

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General (Default) Output

Transit G-force Analysis

User Specified Load


Unit LoadDesign

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Applied Research

Pallet Design & Analysis

Box Design & Analysis

Design for requirements Manufacturability What Materials? Substitutions? Design optimization

Efficient use of materials Lifecycle cost

Analysis vs. testing… Drawings, datasheet, analysis

results

Product Differentiation Checklist

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Stretch Wrap

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Box Crush Testing

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• 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

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Unit Load Research –Block Pallet Testing

page025 Laboratory grade block pallets for testing


Full Scale testing

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Stringer Pallet Unit Load Testing Racked Across Width

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Analytical Model

Laboratory Test


Load Sharing During Racking Across Width

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A portion of the load is carried by the boxes and a portion is supported by the pallet

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Racked Across Length, Medium Boxes, Peri. Base Block PalletBox Compression Stress

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B0 – Extremely Flexible

B1 – 0.375” top deck

boards, 0.5” elsewhere

B2 – 0.5” boards

B3 – 0.625” boards

B4 – 0.75” boards

B5 – 0.5” boards,

unidirectional base

40% increase in box stress for RAL with half as thick boards

Higher stress under 2nd

pallet due to missing boards

Pallet Designs Tested

Critical Box Compression

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Racked Across Length, Medium boxesPallet Stress

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Big reduction in stress

Questions & Answers

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Thank You.

Fredells Travaru AB

Super Global

Documents

Wood Pallets and Unit Load Design: An International …...9/20/2018 1 Wood Pallets and Unit Load Design: An International Expansion National Wooden Pallet & Container Association Welcome