End-loaded split

The pure mode II interlaminar fracture testing can be performed using both the end notched flexure (ENF) specimen (Russell and Street, 1984, 1985) and the end loaded split (ELS) specimen (Corleto and Bradley, 1987 Prel et al.. 1989) (Fig 3.32). 

Whilst test methods to measure the mode I fracture resistance of polymer fibre-composites [1] and stmctural adhesive joints [2,3] have now proceeded to full standards, the efforts to standardise a mode II method have been beset by a number of problems. Firstly, there exist a number of competing tests e.g. the end-loaded split (ELS), the end-notched flexure (ENF), the four point end-notched flexure (4-ENF) and the stabilised end-notched flexure (S-ENF) have all been proposed and have been subjected to various inter-laboratory evaluations. However, the results of these programmes have always revealed a very large scatter in the values of Gnc measured e.g, [4], and this scatter has been variously attributed to friction... 

Fig. 1. The end-loaded split (ELS) test fixture and adhesive joint specimen.

Dynamic Z,S—End-loaded split specimens were also tested in the drop tower, but were mounted horizontally in a custom clamping fixture as shown in Fig. 2. This fixture consists of a side grooved Palmgren vise (Chicago, IL) mounted to a custom pedestal. The pedestal is constructed of 50 x 50 mm steel box tubing welded to 6.4 mm steel plates and is clamped to the drop tower base using 100 mm C-clamps. In this case, a hemispherically-tipped steel tup is attached to the drop tower sled and travels downward, striking the end of the specimen as shown in the schematic in Fig. 2. 

Wang Y, Williams J.G. (1992), Composites Sci. Technol., 34, 251 Blanco N, Gamstedt E K, Costa J, Trias D Analysis of the mixed-mode end load split delamination test (2006) Composite Structure 76, 14-20. 

Multi-stage Multi-stage pumps may be either end-suction or horizontal split-case pumps. They have two basic impeller configurations, in-line or opposed, as shown in Figure 44.23. In-line impellers generate high thrust loads. 

In a shear cell, such as the Jenike shear cell,22 the test powder is consolidated in a shallow cylindrical chamber which is split horizontally. The lower half of the cell is fixed and a shear force is applied to the upper moveable part at a constant low rate (see example E5, section 7.5.5, where experiments were obtained at a constant rate of 0.03 rpm, corresponding to a linear velocity of 1 mm min-1). Shearing can be carried out for each of a series of normal loads on pre-consolidated samples, so that at the end of the test the relationships between the shear stress and normal stress at various bulk densities are obtained. 

The secondary selective circuit arrangement is recommended for all critical loads (Fig. 2). It requires the installation of double-ended switchgear or a variation thereof. Double-ended switchgear includes two main circuit breakers that serve separate feeder buses with a tie circuit breaker in the middle. Each feeder bus has its own set of feeder or branch circuit breakers. The load should be evenly split between each of the feeder buses. 

For members subjected to bending, the value of the modulus of rupture % rather than tensile splitting strength f is used in design. The modulus of rupture is measured by testing to failure, plain concrete beams 6 in. square in cross-section having a span of 18 in. and loaded at two points, each 16 in. equidistant from the end supports of the beam (ASTM C-78). 

Fig. 17 shows the Jenike shear cell in a schematic diagram a circular (internal diameter 95 mm), open-ended shear box is split horizontally, the base is immobile and the ring can slide freely in the horizontal direction. The normal stress, which is applied via the lid, is first used to consolidate the specimen and then to load it during test. 

---