1、DC 62419 : 620.176.25 DEUTSCHE NORM February 1982 I I - DIN 53 295 Testing of sandwiches Peel test by means of a drum Prfung von Kernverbunden; Trommel-Schlversuch Supersedes March 1973 edition As it is current practice in standards published by the International Organization for Standardization (IS
2、O), the comma has been used throughout as a decimal marker. Dimensions in mm 1 The test method according to this standard is intended for determining the resistance of sandwiches to peeling forces acting perpendicular to the face. The peel test by means of a drum is applicable for sand- wiches the f
3、ace of which can be coiled round the drum (see clause 4); the noncoiled part of the sandwich (core and second face) must have a sufficient flexural strength. Field of application and purpose 2 Concepts See also DIN 53 290 Testing of sandwiches; concepts 2.1 The mean specific peeling moment M is a me
4、an value referred to the specimen width of the torques act- ing at peeling during the peel test with the test device specified in subclauses 5.1 and 5.2 3 Designation of the method Designation of the method to be applied in the peel test by means of a drum (A): Peel test DIN 53 295 - A 4 The face of
5、 a sandwich specimen is “peeled“ with a con- stant radius from the core and coiled round a cylindrical drum. From the beginning to the end of the peeling pro- cess the forces are measured and recorded. Brief description of test method 5 Apparatus 5.1 Testing device A tensile testing machine accordin
6、g to DIN 51 221 Part 3 must be used complying with the requirements of class 1 as specified in DIN 51 221 Part 1. The force measuring device and the force indicating device shall have the lowest possible inertia. 5.2 Peeling device For peeling a device in accordance with the construction arrangement
7、 horizontally positioned arrangements are also customary; in these cases the counterweight can be omitted. The suspended arrangement shall consist of a drum with lateral flanges and a clamping device for the test piece. Steel strips shall be fixed to the flanges; for force appli- cation the free end
8、s of the steel strips shall be provided with a yoke. For a suspended arrangement the counter- weight on the drum must be dimensioned so that equi- librium around the rotational axis of the drum is estab- lished. The total weight of the device shall not exceed 3 kg. / / Flange III The peeling device
9、need no conform to the pictorial repre- sentation; only the dimensions specified must be adhered to; dimensions in brackets are left U -IFoa3 Clamping device Steel strip 3 Il I 1 Force application yoke example shown in figure 1 shall be used for a suspended Figure 1. Peeling device for sandwiches wi
10、th longi- tudinally orientated structural units, a minimum of three, in the case of cellular structural units, a minimum of nine shall be contained in the specimen width. 8 Procedure Thespecimen width shall be measured to 0,l mm. The specimen with its free end shall be fixed to the drum, the other e
11、nd shall be clamped in the upper grip of the tensile testing machine and the force indication of the testing machine shall be set to zero. The yoke of the peeling device shall be then clamped in the lower grip. In the case of horizontally positioned arrangements proceed appropriately. After the appl
12、ication of a preload for adjusting the peel- ing device peeling shall take place, the speed of the draw- ing grip being 25mm/min. By means of the recording device of the testing machine the force for peeling shall be recorded in a forcehinear deformation diagram (peeling diagram). When doing so, it
13、must be taken into account that the recording of the rapid changes in force in the peeling diagram shall not be falisified by the damping of the measuring device. Specimen width b = 75 Figure 2. Test piece 6.2 Sampling or manufacturing of specimens The specimens shall be either taken from the sandwi
14、ch plate to be tested with the corresponding dimensions or shall be manufactured appropriately applying DIN 53 281 Part 1 and 2. 6.3 Number The number of the specimens tested shall be not less than three. 6.4 Preconditioning The specimens must be preconditioned before testing. Test pieces with core
15、or face materials having material properties dependent on the moisture content, shall be stored for at least 48 hours - in arbitration cases until approximately constant weight is obtained in an agreed standard atmosphere according to DIN 50 014. Constant weight is deemed to be reached when the weig
16、ht, related to the hygroscopic components of the sandwich, changes by no more than 0,5 % between two weighings at an interval of at least 24 hours. Test pieces with non-hygroscopic cores and face materials shall be only adjusted to the temperature of the standard atmosphere according to DIN 50 014.
17、Note: For sandwiches with non-hygroscopic faces and cores also the strength and deformation properties of the sandwich can be affected by a hygroscopic adhesive layer. 7 Preparation Before the peel test by means of a drum, the length, width height and core height and face thickness must be determine
18、d, with a maximum deviation of 1 %from the measured value. 9 Evaluation Evaluation shall be done by using the peeling diagram (see figure 3). For determining the mean tensile forcep, only forces measured in the central range of the specimen length, shall be taken into account. The first and last 10%
19、 of the diagram length must not be used for the evaluation. Note: The diagram length depends on the type and the transmission of the test machine recording device. The mean specific peeling momentM shall be calculated from the following equation: ( this force must be determined by pretests ra is the
20、 flange radius plus half the steel strip thickness in mm 125+a ra = _ 2 100 + t ri = - 2 b is the specimen width in mm ri is the drum radius plus half the face thickness in mm Not evaluated DIN 53 295 Page 3 10 Test report With reference to this standard the test report must include the following in
21、formation: type and designation of the product tested material and thickness of the faces material, thickness and density of the core, if applic- able, direction of anisotropies in the core and the face type of bonding between core and faces with characteristic details type of sampling dimensions of
22、 the specimens in mm if applicable, pretreatment of the joining surfaces of the joining parts according to DIN 53 281 Part 1 and for data on metallic joining parts the bonding process according to DIN 53 281 Part 3 number of specimens storage conditions prior to testing (temperature, atmosphere) if
23、applicable, storage conditions until constant weight is achieved test conditions (temperature, atmosphere) type of testing machine and range of force measure- ment type of failure N mm specific peeling momentM in - mm individual values and arithmetic mean, rounded to three significant digits at leas
24、t one peeling diagram if applicable, deviations from this standard date of test. Standards referred to DIN 50 014 Atmospheres and their technical application; standard atmospheres DIN 51 221 Part 1 Material testing machines; tensile testing machines; general requirements DIN 51 221 Part 3 Material t
25、esting machines; small tensile testing machines DIN 53 281 Part 1 Testing of adhesives for metals and bonded metal joints; specimens: pretreatment of joining surfaces DIN 53 281 Part 2 Testing of adhesives for metals and bonded metal joints; specimens; manufacture DIN 53 281 Part 3 Testing of adhesi
26、ves for metals and bonded metal joints; specimens; data of the bonding process DIN 53 290 Testing of sandwiches; concepts Previous editions DIN 53 295: 03.73 Amendments Compared with the March 1973 edition, the following amendments have been made: the contents have been revised editorially. Explanations This standard was prepared by Technical Committee NMP 456 “Testing of sandwiches“ of Normenausschuss Materialprfung (NMP) (Materials Testing Standards Committee).
