Butt tensile test

Fig. 16. The results of Dyckerhoff and Sell for inlerfacial strengths measured hy butt-tensile tests for various lacquers (adhesives) against various plastics as a function of the surface energy, ys of the plastics. Arrows indicate the surface tensions of the adhesive, y, used in the generation of each curve, showing rough agreement with the requirement that a maximum in adhesion is achieved when yt ys (I kp/cm- 0.1 MPa). Redrawn from ref. [71. ...

Figure 9 Butt tensile test (a) sample preparation (b) tensile tester set-up (c) 45° mirror set-up. Copyright 2003 by Taylor Francis Group, LLC...

Figure 10 Typical butt tensile test graphs (a) undercured, (b) cross-linked, (c) overcured, and (d) block copolymer adhesives (e) stages in the cross-linking of a pressure-sensitive adhesive. 

Fig. 21. Penny-shaped debond in a butt tensile test geometry.

Butt, tensile test using compression moulding (see Figure 3.22). This is not widely used in rubber to metal bonding. 

McCann and Johnston initially looked at three test configurations for butt tensile tests a metal probe brought into contact with the adhesive surface on a flat plate a rectangular, flat metal probe with the adhesive tape wrapped around the panel and secured, then brought into contact with a test surface and two rectangular, flat faced panels with adhesive tape wrapped around both panels, brought together adhesive-to-adhesive. 

ISO 11003-1 2001 Adhesives - Determination of shear behaviour of structural adhesives -Part 1 Torsion test method using butt-bonded hollow cylinders ISO 11003-2 2001 Adhesives - Determination of shear behaviour of structural adhesives -Part 2 Tensile test method using thick adherents ISO 13445 2003 Adhesives - Determination of shear strength of adhesive bonds between rigid substrates by the block-shear method... 

Butt tensile—adhesives. Bolt shaped specimens were bonded and cured as for the surface coating specimens and tested in the same way. 

The effect of silanes on the bond strength of two epoxide adhesives to glass is shown in Table 13. The test mode was that of Sandwich Butt Tensile in which a glass disc was bonded between two aluminium specimens in the form of a sandwich, and the resulting composite specimen broken on an Instron Universal Test Machine. Clearly in such a composite test specimen, alignment is important and there are many potential sites and modes of failure. 

The ASTM D 897 tensile button test is widely used to measure the tensile strength of a butt joint made with cylindrical specimens (Fig. 20.3). The tensile strength of this bond is defined as the maximum tensile load per unit area required to break the bond (measured in pounds per squre inch). The cross-sectional bond area is usually specified to be equal to 1 in.2. The specimen is loaded by means of two grips that are designed to keep the loads axially in line. The tensile test specimen requires considerable machining to ensure parallel surfaces. 

Despite the fact that adhesive joints are rarely designed to be loaded directly in tensile mode, tensile tests are eommon for evaluating adhesives. The axially-loaded butt (or poker chip ) joint geometry, as recommended by ASTM D897(52), is depicted in Fig. 4.11. 

Fig. 4.11. Tensile (cylindrical) butt-joint test, (a) Unloaded, (b) Loaded, (c) Stress distribution.

Finite-element methods have also been used to evaluate new test equipment to measure shear strength under impact loads. In the equipment, two rectangular plates, bonded opposite faces of a vertical hexagonal prismatic rod, bear on a firm surface. The top of the central rod is subjected to an impact load. To prove the validity of the method, the maximum shear stress was compared with the impact shear strength, which was measured using a cylindrical butt joint subjected to impact torsional loads (see Tensile tests). 

The two main types of filled joints are butt joints and lap joints (Fig. 2) (see Shear tests and Tensile tests) each has advantages and disadvantages. The lap joint gives the sealant some protection against the weather, and a further advantage of this type of joint... 

Tensile tests were made at 75°F on all three groups of materials and at -300 F on two groups—the unwelded plate and the butt welded plate with the beads machined off-to determine the ultimate strength, yield strength and percent elongation. A minimum of three specimens per group for each test temperature was used. 

In the long-term tensile test on tensile test bars with dual hot wedge seams and extrusion fillet seams the plane of the seam is not perpendicular to the tensile direction, as in butt welded pipe seams, but parallel. The force flow in the loaded specimen is directed over the weld seam from one geomembrane into the other in an offset direction, therefore force flow lines get more dense in the boundary region of the weld seam and a stress concentration develops. In the boundary region there are also noteh effects induced by the transition from the welded material area to the base material. A eraek that develops there... 

Another tensile test, ASTM D2095-72, involves the testing of bar and rod butt joint specimens. ASTM 2094-69 describes the preparation of these specimens (see Figure 3). This test and the samples can be used with substrates comprised of metals, plastics, or reinforced plastics. Loads are applied through fixtures connected to the samples by dowel pins. The standard test rate is 2400 to 2800 lb per square inch of bond area. The maximum load at failure is used to calculate the tensile strength, the same as for the pi-tensile specimens. 

Probe test, in which the tip of a probe is brought into contact under low pressure for a short time. The probe is withdrawn at a defined speed, and the butt tensile strength is measured. 

When the AS 1160 resin is mixed with isocyanate, and cured for up to 24 h in dry (typically less than 15 % RH), a thixotropic polyurethane adhesive is formed. The adhesive is commercially used to bond metals, organic and inorganic materials, and is particularly useful for reducing the relative movement of components in multimaterial assemblies. The performance of the polyurethane adhesive requires the ultimate tensile strength (UTS) to be a minimum of 15 MPa when measured using butt tensile specimens by ASTM Test Method D2095. 

The first four of these reasons fall into a category of comparison or quality control testing. For these purposes, it might appear that almost any test could be used as long as care is taken to assure that the test conditions are held constant. However, an adhesive that tests superior to others may appear inferior if a different test is used. For example, some adhesives exhibit relatively high butt tensile strengths, but poor peel strengths, and vice versa. 

---