Shear strength tests

Table 1 contains the metal-to-metal engineering property requirements for Boeing Material Specification (BMS) 5-101, a structural film adhesive for metal to metal and honeycomb sandwich use in areas with normal temperature exposure. The requirements are dominated by shear strength tests. Shear strength is the most critical engineering property for structural adhesives, at least for the simplistic joint analysis that is commonly used for metal-to-metal secondary structure on commercial aircraft. Adhesive Joints are purposefully loaded primarily in shear as opposed to tension or peel modes as adhesives are typically stronger in shear than in Mode I (load normal to the plane of the bond) loading. 

Since the m,m -DABP polyimide is known to be an outstanding adhesive, lap shear strength tests employing titanium-titanium adherends and metal ion filled polyimides were conducted. Tests were performed at room temperature, 250°C and 275°C employing either DMAC or DMAC/Diglyme as the solvent. At room temperature regardless of the metal ion employed adhesive strength is de-... 

Ikuta, N., Maekawa, Z., Hamada, H, Ichihashi, M. and Nishio, E. (1991). Evaluation of interfacial properties in glass fiber-epoxy resin compositcs-reconsideration of an embedded single filament shear-strength test. J. Mater. Sci. 26, 4663-4666. 

Recommended Practice for Metal to Metal Overlap Shear Strength Test for Automotive Type Adhesives... 

Shear Strength Tests of Resin-Bonded Panels. The standard procedures for synthesizing the P/C/U/F types of resins, formulating the resins into final adhesives, and preparing and testing specimens were described previously (9,10). Two experiments that differed from the standard follow. 

Surface-etherified Makamba Beiula maximowieziana Regal) specimens were used for shear strength tests. Other tests used Sugi Cryptomeria japonica D. Don) sap wood. 

Fig.4 Typical load-displacement curve obtained in shear strength test...

After tires are placed and fastened in designated construction area, various types of materials could be used to fill up voids in the structure for providing the required weight to overcome uplifting. Bases on laboratory direct shear strength tests and hydraulic resistance experiments [4], three types of fillings are recommended construction rubble, sand and gravel, and flowable mixture of loess, cement, and sand. 

There are a wide variety of static shear strength tests as shown in Figure 6.19. These various tests differ in the manner of lateral constraint, shearing plane, and whether they are undrained/drained. 

Chandler, R.J. 1988. The in-situ measurement of the imdrained shear strength of clays using the field vane. In Vane Shear Strength Testing in Soils Field and Laboratory studies, ASTM STP 1014, Richards, A.F., ed., American Society for Testing and Materials, Philadelphia, PA, pp. 13-44. 

Chaney, R.C., and Richardson, G.N. 1988. Measurement of Residual-Remolded Vane Shear Strength of Marine Sediments. Vane shear strength testing in soils Field and laboratory studies, ASTM, Philadelphia, PA, pp. 166-181. 

Field vane test Clay Undrained shear strength Test shonld be used with care, particularly in fissured, varved and highly plastic clays ASTM D 2553-72 Bjerrum (1972) Schmertmann (1975) Wroth and Hughes (1973) Wroth (1975) BS 5930 (1999)-Cl 25.3... 

Lap shear strength. Tests should be carried out over a range of temperatures, specifically including -25 °C, +20 °C and +45 °C. using bright mild steel adherends. The temperature should be measured by means of a thermocouple attached to the steel surface of the joint. Two alternative forms of lap shear joint may be employed. 

Continuous scans of modulus versus temperature utilizing the DuPont Dynamic Mechanical Analyzer (DMA) has provided a comparison of the high temperature service capabilities of radiation-cured experimental formulations of a vinyl-modified epoxy resin. Shell Epocryl-12. These scans were compared to data obtained when the same materials were applied as adhesives on aluminum test panels, radiation-cured with an electron beam, and lap shear strength tested at discrete temperatures. The DMA instrument utilizes a thin rectangular specimen for the analysis, so specimens can be cut from blocks or from flat sheets. In this case the specimens were cured as sheets of resin-saturated graphite-fibers. The same order of high temperature stability was obtained by each method. However, the DMA method provided a more complete characterization of temperature performance in a much shorter test time and thus, it can be very useful for quick analyses of formulation and processing variables in many types of materials optimization studies. The paper will present details of this study with illustrations of the comparisons. 

Pig. 1. Adhesive Evaluation Lap Shear Strength Test Results - LARC-13... 

Shear strength Maximum shear stress that can be sustained by material before rupture, determined in a torsion test, equal to the torsional strength. A much simpler but less acurate method is the interlaminar shear strength test (ILSS). 

Fig. 1. Comparison of destructive shear strength tests on laminates with the predicted strengths using a Fokker bond tester. A series of laminates is represented where the adherend thickness t varies as follows ( ), t = 0.6 mm (O), t = 0.8 mm (x), f = 1.0 mm (-h), f = 1.2 mm (A), t = 1.5 mm. To construct this standard plot, 120 specimens of Dural 2024-T3 were used 95% of all results are within the range 0.36 kg mm . (From R J Schliekelmann, Non-destructive testing of adhesively bonded joints, in Adhesion, Fundamentals and Practice, McClaren, London, 1966)...

Figure 24.15 Comparison of force-deflection curves recorded in interlaminar shear strength tests between composites made with commercial glass fibers (as received) and fibers coated with the Pyre...

In addition to inter-laminar shear strength tests to evaluate the static mechanical performance of the composites, fatigue testing was carried out, since not only must the plate carry gross loads, but must also be able to withstand cyclic loads dutj ng the working cycle. Mechanical test results have been reported and the fatigue studies are to be reported in detail elsewhere... 

Experiment P should, in fact, score slightly overO.4, in view of the lecture schedule. The result for experi ment R, however, is somewhat surprising, since all teams were formally lectured on soil strength after they had performed the shear strength test in the laboratory. A result close to 0.0 could therefore be expected. Previous exposure to the concept of friction and to strength criteria in other courses may explain the value of 0.3. 

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