Test method for climbing drum peel strength of sandwich constructions
1 Scope
This document specifies the test principle, test equipment, samples, test conditions and status conditioning, test procedures, test results and processing and test report of climbing drum peel strength of sandwich constructions.
This document is applicable to peel strength determination of sandwich constructions of flexible facings, and of other assemblies with adhesive.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute indispensable provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 1446 Fiber-reinforced plastics composites — The generals for determination of properties
GB/T 3961 Terms for fibre reinforced plastics
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 3961 and the following apply.
3.1
climbing drum peel strength
anti-peel torque per unit width at the time of the facing separated from the core
3.2
nominal climbing drum peel strength
climbing drum peel strength without compensating facing resistance force load
3.3
resistance force
load required to resist facing bending and drum climbing during the test
4 Test principle
The anti-peel strength of the connection between the facing and the core is measured by peeling the facing from the sandwich construction with a flanged drum. One end of the peeled facing is connected with the drum and the other end is connected with the upper fixture. The flange is connected with the lower fixture through loading steel tape, and static tensile load is applied at a uniform speed along the axial direction of the sample. The torque difference is generated between the flange and the climbing drum, thus peeling the facing from the sandwich construction.
5 Test equipment
5.1 The test machines shall meet the requirements in GB/T 1446.
5.2 Drum peeling device: the diameter of the drum is 100 mm ± 0.10 mm, the diameter of the drum flange is 125 mm ± 0.10 mm, and it is made of aluminum alloy material, with the mass less than 1.5 kg; the drum shall be balanced along the axis by machining relief holes or balance blocks; the loading tape is a flexible steel tape or cable. Figure 1 shows a typical climbing drum peeling device.
Keys:
1——Upper fixture;
2——Drum flange;
3——Sample;
4——Loading tape;
5——Lower fixture.
Figure 1 Typical climbing drum peeling device
5.3 Vernier caliper, with an accuracy of 0.01 mm.
6 Samples
6.1 The sample shall be processed according to GB/T 1446, and its shape and dimension are shown in Figure 2. The thickness h of the sample is the same as that of sandwich construction products; in case of uncertain product thickness, the sample thickness of 20 mm, and the facing thickness tf of not greater than 1 mm are recommended. The recommended sample width b is 60 mm; for lattice cores such as honeycomb and corrugated, the recommended sample width is 80 mm if the lattice edge length is greater than 8 mm or the wave distance is greater than 20 mm.
mm
Keys:
1——Non-peeled facing;
2——Core;
3——Peeled facing;
tf——Facing thickness;
h——Sample thickness;
b——Sample width.
Figure 2 Shape and dimension of sample
6.2 For orthogonal anisotropic sandwich constructions, samples shall be divided into longitudinal and transverse types.
6.3 For sandwich construction products formed by wet process, the sample shall be divided into two types: peeling upper facing and peeling lower facing.
6.4 If the sample thickness is less than 10 mm or the sample bending stiffness of the sandwich construction is small, the non-peeled facing shall be bonded with wood or other reinforcing materials with a thickness greater than 10 mm, as shown in Figure 3. The bonding curing temperature shall be room temperature or at least 30°C lower than the bonding curing temperature of sandwich construction.
Keys:
1——Reinforcing materials;
2——Sample.
Figure 3 Sample of bonded with reinforcing material
6.5 The non-peeled facing and core at both ends of the sample shall be cut 30 mm each, leaving the peeled facing (see Figures 2 and 3) for connection with the drum and fixture (see Figure 1).
6.6 The material, thickness and width of the facing sample used for resistance force test shall be consistent with that of the peeled facing, or determined by the peeling condition after the peeling test. The facing with an adhesive layer, if separated from the sandwich construction, shall be cut from the sandwich construction for resistance force test.
Note 1: The resistance force test is to test a single facing with a climbing drum to obtain the resistance force load required to resist the facing bending and the drum climbing.
Note 2: The resistance force load of partial sandwich construction peeling (such as low-density core sandwich) is affected by factors such as facing, drum and adhesive layer.
6.7 The quantity of samples shall meet the requirements in GB/T 1446.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Test principle
5 Test equipment
6 Samples
7 Test conditions and status conditioning
8 Test procedure
9 Test results and processing
10 Test report
Bibliography
