Pallets for materials handling — Flat pallets — Part 4: Procedure for predicting creep responses in stiffness tests for plastic pallets using regression analyses

ISO 8611-4:2013 presents a procedure for predicting creep responses in stiffness tests for plastic pallets to shorten the test period. Based on regression analyses, deflections during full load and relaxation periods are predicted. ISO 8611-4:2013 is for use with the static stiffness tests such as tests 1b, 3b, 4b, 5b, and 7b referred to in ISO 8611-1:2011, and is for application at ambient temperature only.

Palettes pour la manutention — Palettes plates — Partie 4: Mode opératoire pour prédire les réponses au fluage lors des essais de rigidité des palettes en plastique en utilisant des analyses de régression

General Information

Status
Published
Publication Date
24-Sep-2013
Current Stage
9093 - International Standard confirmed
Start Date
04-Nov-2013
Completion Date
26-Jan-2021
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ISO/TS 8611-4:2013 - Pallets for materials handling -- Flat pallets
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TECHNICAL ISO/TS
SPECIFICATION 8611-4
First edition
2013-10-15
Pallets for materials handling — Flat
pallets —
Part 4:
Procedure for predicting creep
responses in stiffness tests for plastic
pallets using regression analyses
Palettes pour la manutention — Palettes plates —
Partie 4: Mode opératoire pour prédire les réponses au fluage
lors des essais de rigidité des palettes en plastique en utilisant des
analyses de régression
Reference number
ISO/TS 8611-4:2013(E)
ISO 2013
---------------------- Page: 1 ----------------------
ISO/TS 8611-4:2013(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2013

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
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Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 8611-4:2013(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Symbols and abbreviated terms ........................................................................................................................................................... 2

5 Procedure for predicting creep responses ................................................................................................................................ 2

5.1 Purpose .......................................................................................................................................................................................................... 2

5.2 Test procedure ......................................................................................................................................................................................... 3

5.3 Specification of regression models ........................................................................................................................................ 3

5.4 Predicting the deflections under the test load and during the relaxation time .............................. 4

5.5 Statistical testing for the standard performance limit.......................................................................................... 5

6 Test report ................................................................................................................................................................................................................... 6

Annex A (informative) An example of predicting creep responses in order to reduce the full test

load duration ............................................................................................................................................................................................................ 7

Bibliography .............................................................................................................................................................................................................................10

© ISO 2013 – All rights reserved iii
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ISO/TS 8611-4:2013(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers

to Trade (TBT) see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 51, Pallets for unit load method of materials handling.

ISO 8611 consists of the following parts, under the general title Pallets for materials handling — Flat pallets:

— Part 1: Test methods
— Part 2: Performance requirements and selection of tests
— Part 3: Maximum working loads

— Part 4: Procedure for predicting creep responses in stiffness tests for plastic pallets using regression

analyses [Technical Specification]
iv © ISO 2013 – All rights reserved
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TECHNICAL SPECIFICATION ISO/TS 8611-4:2013(E)
Pallets for materials handling — Flat pallets —
Part 4:
Procedure for predicting creep responses in stiffness tests
for plastic pallets using regression analyses
1 Scope

This part of ISO 8611 presents a procedure for predicting creep responses in stiffness tests for plastic

pallets to shorten the test period. Based on regression analyses, deflections during full load and

relaxation periods are predicted. This part of ISO 8611 is for use with the static stiffness tests such as

tests 1b, 3b, 4b, 5b, and 7b referred to in ISO 8611-1:2011, and is for application at ambient temperature

only. Annex A gives an informative example of this process.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 445, Pallets for materials handling — Vocabulary

ISO 8611-1:2011, Pallets for materials handling — Flat pallets — Part 1: Test methods

ISO 8611-2:2011, Pallets for materials handling — Flat pallets — Part 2: Performance requirements and

selection of tests
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 445 and the following apply.

3.1
regression analysis

statistical technique for modelling and analysing the relationship between several variables, where the

focus is on the relationship between a dependent variable and one or more independent variables

3.2
least square method

statistical method of estimating the coefficients in the regression model such that the sum of squared

residuals are minimized, where the residual is the difference between an observed value and the value

provided by the model
3.3
test period

period required for the stiffness test of plastic pallets, which is divided into full test load period and

relaxation period
3.4
full test load period

full period required for the stiffness test of plastic pallets under load, which lasts for 24 h or 48 h

depending upon the type of tests
© ISO 2013 – All rights reserved 1
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ISO/TS 8611-4:2013(E)
3.5
relaxation period

period required for the stiffness test of plastic pallets after releasing load, which lasts for 2 h from the

outset of releasing
3.6
reduced test period

reduced period required for the stiffness test of plastic pallets under load, which lasts for 4 h

3.7
relaxation period of the full test

period required for the stiffness test of plastic pallets after releasing load, which lasts for 2 h from the

end of the full test load period
3.8
relaxation period of the reduced test

period required for the reduced stiffness test of plastic pallets after releasing load, which lasts for 2 h

from the end of reduced full load period
4 Symbols and abbreviated terms
b, b regression coefficients
0 1
b*, b * estimated regression coefficients
0 1
Y(t)* deflection predicted at time t (mm)
Y(t) deflection actually measured at time t (mm)
e(t) regression error at time t
ln(t) natural logarithm of time t
5 Procedure for predicting creep responses
5.1 Purpose

Stiffness tests for plastic pallets, including tests 1b, 3b, 4b, 5b, and 7b in ISO 8611-1:2011, require test

durations of 24 h to 48 h, depending on the type of test measurement. These test durations are essential

because plastic pallets and pallet decks creep while placed in storage racks or stack storage. However, it

is of great benefit in saving time and cost if creep deflections can be predicted for the entire test period

from the test data of the first 4 h. Using the method described in this part of ISO 8611, test duration can

be reduced while keeping the same time of relaxation as in ISO 8611-1:2011, as recommended in Table 1.

This part of ISO 8611 shows how to conduct the stiffness tests based on the predicted value of creep

responses during the loading and relaxation periods.

Table 1 — Full load duration and reduced duration recommended for static stiffness tests

Pallet material and tests Test period Reduced test Relaxation
(h) period time
(h) (h)
Where plastics or plastic parts dictate tests 1b, 3b, 5b, and 24 4 2
overall performance 7b
test 4b 48 4 2
2 © ISO 2013 – All rights reserved
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ISO/TS 8611-4:2013(E)
5.2 Test procedure

At least three plastic pallets for each test shall be used as specified in Clause 5 of ISO 8611-2:2011. Deflections

at the specified locations on the pallet shall be recorded continuously during the creep test. The frequency

of 1 observation per 30 s is recommended for the first hour of testing, and the recommended frequency

for the remainder of the creep test is 1 every 10 min interval. The recommended extraction interval for

relaxation is 1 observation every 30 s. The following steps shall be used to predict the creep responses.

1) Test the first pallet for both the full load period (24 h; 48 h for test 4b) and the relaxation period

(2 h). Deflections at specified intervals shall be measured while pallet creeps. If the deflection

measured at the end of the full load or the relaxation period exceeds the standard performance

limits specified in Table 1 of ISO 8611-2:2011, stop the test. The pallets in the lot shall be declared as

failed for the stiffness test. Otherwise, proceed with step 2.

2) Test the second pallet for the reduced test duration with 4 h load. Use Formula (1) to estimate the

regression coefficients for the loading test period. Then predict the deflections for the remainder

beyond the reduced test duration, which span from 4 h to 24 h (or 48 h), based on Formula (1). If

the deflection predicted at the end of the
...

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