BS EN 1007-5:2010 pdf free.Advanced technical ceramics – Ceramic composites Methods of test for reinforcements Determination of distribution of tensile strength and of tensile strain to failure of filaments within a multifilament tow at am bient temperature.
BS EN 1007-5 A multifilament tow is loaded in tension. The test is performed at a constant displacement rate up to failure of all fibres. Force and cross-head displacement are measured and recorded simultaneously. When required, the longitudinal deformation is derived from the cross-head displacement using a compliance correction. From the force-displacement curve, the two-parameter Weibull distribution of the rupture strain and the distribution of the rupture strength of the filaments are obtained by sampling the non-linear parts of the curve at discrete intervals j, which correspond to an increasing number of failed filaments in the tow. The test duration is limited to reduce time dependent effects.
The measurement of strain directly on the tow is dificult, so it is usually achieved indirectly via a compliance measurement that includes contributions of the loading train, grips, tab materials, etc. When it is possible to measure the tow elongation directly (by using a suitable extensometer system) this correction is not needed. The calculation of the results in Clause 10 also applies in this case by setting the load train compliance equal to zero.
The evaluation method is based on an analysis of the non-linear increasing and decreasing parts of the forcedisplacement curve, which are caused by progressive filament failure during the test. The occurrence of these stages is promoted by a higher siffness of the loading and gripping system. This method of evaluation is only applicable when the force-displacement curve shows these non-linear parts.
The distribution of filament rupture strains does not depend on the number of filaments in the tow and is hence not affected by the number of filaments that are broken before the test. The determination of the filament strength distribution and of the elastic modulus necessitates knowledge of the initial cross sectional area of the tow.
Because the number of unbroken filaments within the tow prior to the test is usually unknown, the values for the filament strength and for the elastic modulus necessarily represent lower bounds to these quantities. Also, the variation in filament diameter, which affects the strength values, is not accounted for.
The test machine shall be equipped with a system for measuring the force applied to the specimen and the displacement, or directly the tow elongation.Additionally, the machine shall be equipped with a system for measuring the crosshead displacement with accuracy better than 1 um.BS EN 1007-5 pdf download.