ISO 17194 pdf download – Structural adhesives – – – Standard database of properties.
NOTE 1 Strain at failure for ductile inatenals is measured alter yield and therefore requires the measurement of a nominal strain, The nominal strain is derived from measurements of grip separation instead oF estensometer values. See ISO 527-1:2019. 3.8 and 9.5, for the delinition and measurement of nominal strain.
NOTE 2 See ISO 527.1:2019,3.6.1 and 3.7.1. for definitions of stress and strain at ywld. respectively.
NOTE 3 A wider interest in the toughness of an adhesive relates to a knowledge of the temperature of the transition from ductile to brittle behaviour. This temperature can be derived Iron measurements or toughness, using the cleavage test ISO 11343, as a function of temperature. Related Information can be obtained from measurements of ductility at different temperatures using tests for fracture energy under impact (ISO 179-1 and ISO 179-2) or strain at failure in tensile tests on bulk specimens (see ISO 527).
NOTE 4 The service temperature range will be determined by the criteria used to decide maximum and minimum operating temperatures. Generally, the upper temperature Is decided by the glass transition temperature ; and the lower temperature by the transition from ductile to brittle behaviour, This lower temperature limit can be determined from measurements of toughness or ductility with temperature (see Note 3).
NOTE S The measured value of electric strength is very dependent on the thickness of the adhesive layer.
7.2 Durability in different environments
Data measured using the test method and conditions given in Table 2 reveal the influence on the lap shear strength of the adhesive of exposure to different environments. The tolerance on the test and exposure temperatures specified in TabIt2 shall be ±3 °C. except at 23 °c where the tolerance shall be ±2 °C. Results obtained using the conditions specified in the first row of the table show the dependence of shear strength on temperature separately from the effects ofany ageing. In subsequent rows, specimens are subjected to exposure for 30 days in the environments shown and then tested at (23 ± 2) °C. The procedure for conditioning specimens shall be in accordance with ISO 9142 tór the procedure for conditioning specimens. Where It Is known that a particular adhesive Is not recommended for use with the chemicals shown in Table 2. then the letters NR shall be given in place of experimental values.
Record cure temperature, cure time, post-cure temperature and post-cure time used for specimen preparation. Also record adherend material and surface treatment (see ISO 17212).
7.3 Simple stress analysis
Data obtained by the tests recorded in Table 3 are required for carrying out calculations of stress and strain distributions in the adhesive in a bonded joint under load, For example using finite-element analysis. If an elastic analysis is carried out, only the first three rows of data are needed, Data specified by the fourth and fifth row or a complete stress vs strain curve are required for a stress analysis that takes account of plastic deformation using an elastic-plastic model appropriate for adhesive and in general polymer materials with the ability to properly consider hydrostatic Stress effects.
Property values shall be recorded at 23 C and, optionally, at additional temperatures to allow stress analysis calculations of behaviour at other temperatures.
Table 3 — Properties required for a simple stress analysis
NOTE I In order to characterize elastic behaviour for a stress analysis, values are needed ortensile modulus and Poicson’.s ratio. These arc most conveniently obtained 1mm tests on bulk specinwns II bulk specimens are not avaiLable, a value for the shear modulus can he obtained from a thlck-adhcrend shear test (ISO 11003.2) and used with an estimate of Poissons ratio to calculate a valuc for the tensile modulus,
NOTE 2 A stress/strain curve Is required to characterize the non.llnear behaviour
ISO 17194 pdf download – Structural adhesives – – – Standard database of properties
