Composites Mechanical testing

THROUGH THICKNESS MODULUS (E33) OF CERAMIC MATRIX COMPOSITES MECHANICAL TEST METHOD CONFIRMATION... 

Ojard, G., Barnett. T., Calomino, A., Gowayed, Y., Santhosh, U., Ahmaad, J., Miller, R., and John, R. Through Thickness Modulus (E33) of Ceramic Matrix Composites Mechanical Test Method Development , Ceramic Engineering and Science Proceedings. Vol. 27, no. 2, pp. 331-340.2007... 

Through Thickness Modulus (E33) of Ceramic Matrix Composites Mechanical Test Method Confirmation... 

Single-fiber pull-out tests, and Composite mechanical testing. 

Various tests and analytical methods are used for the characterisation and evaluation of the properties of vegetable oil-based polymer composites. Mechanical tests for properties such as tensile, flexural, compressive, impact, hardness and wear are carried out by a universal testing machine (UTM), and by equipment for testing impact, hardness, abrasion loss, and so on. Weather and chemical resistance tests are performed in UV/ozone, an artificial environmental chamber and in different chemical media. Water uptake and biodegradability tests are carried out by standard ASTM methods. Biodegradability and biocompatibility may be studied by the same procedure as described in Chapter 2. However, in practice only a few such studies have been performed for vegetable oil-based composites. 

R.W. Davidge and J.J.R. Davies, "Ceramic Matrix Fibre Composites Mechanical Testing and Performance", Int. J. High Tech. Ceram., [4] 341 (i988)... 

AWS) has issued specifications covering the various filler-metal systems and processes (2), eg, AWS A5.28 which appHes to low alloy steel filler metals for gas-shielded arc welding. A typical specification covers classification of relevant filler metals, chemical composition, mechanical properties, testing procedures, and matters related to manufacture, eg, packaging, identification, and dimensional tolerances. New specifications are issued occasionally, in addition to ca 30 estabUshed specifications. Filler-metal specifications are also issued by the ASME and the Department of Defense (DOD). These specifications are usually similar to the AWS specification, but should be specifically consulted where they apply. 

The American Society for Testing and Materials (ASTM) F4 Committee on Medical Materials and Devices has developed specifications for chemical composition, mechanical properties, and other factors. Standard test methods also are available from ASTM, 1916 Race Street, Philadelphia. The quaHty of castings is important for dental implants, and standards to define this would be useful. 

The turbine undergoes three basic tests, these are hydrostatic, mechanical, and performance. Hydrostatic tests are to be conducted on pressure-containing parts with water at least one-and-a-half times the maximum operating pressure. The mechanical run tests are to be conducted for at least a period of four hours at maximum continuous speed. This test is usually done at no-load conditions. It checks out the bearing performance and vibration levels as well as overall mechanical operability. It is suggested that the user have a representative at this test to tape record as much of the data as possible. The data are helpful in further evaluation of the unit or can be used as base-line data. Performance tests should be conducted at maximum power with normal fuel composition. The tests should be conducted in accordance with ASME PTC-22, which is described in more detail in Chapter 20. 

A significant amount of waste composites is generated each year and the need for a recycling method is becoming a necessity. Environmental Technical Services has developed, with the support of the University of Missouri-St.Louis, a method for recovering valuable constituents from composite materials. The process converts the polymer matrix to lower chain hydrocarbons and fuel gas leaving behind fibres. Mechanical tests of BMC panels, reinforced concrete and compression moulded panels made with recovered fibres were carried out. 10 refs. USA... 

Mechanical Property Testing. Mechanical tests were performed on both unirradiated and irradiated materials at -157°C, 24°C, and 121°C. Specimens were kept dry prior to testing in an environmental chamber mounted in a tensile testing machine. Tensile test specimens of [0]4, [10]4, [45]4, and [90]4 laminates were cut from 4-ply composite panels. All specimens were straight-sided coupons. For tension and shear tests the length/width aspect ratio was 8. For the compression tests the aspect ratio was 0.25 and the unsupported length was 0.64 cm. The [0]4 laminates were used to measure the ultimate tension and compression strength, Xit the axial... 

Ananth, C.R. and Chandra, N. (1995). Numerical modelling of fiber push-out test in metallic and intermetallic matrix composites mechanics of failure process. J. Composite Mater. 29, 1488-1514. 

Hirschbuehler, K.R. (1987). A comparison of several mechanical tests used to evaluate the toughness of composites. In Toughened Composites, ASTM STP 937 (N.J. Johnston ed.), ASTM, Philadelphia, PA, pp. 61-73. 

Cook, J. (1970). Mechanical testing of whiskers. Composites, March, 176—180. 

Moore, D., Pavan, A., and Williams, J. 2001. Fracture Mechanics Testing Methods for Polymers, Adhesives, and Composites. Elsevier, New York. 

Figure 5.112 Idealized stress-strain curve for a tough ceramic-matrix composite. Reprinted, by permission, from R. W. Davidge and 1. J. R. Davies, in Mechanical Testing of Engineering Ceramics at High Temperatures, B. F. Dyson, R. D. Lohr, and R. Morrell, eds., p. 251. Copyright 1989 by Elsevier Science Publishers, Ltd.

Third, in situ sensing is needed to verify the veracity and logic of a model s predictions or an operator s reasoning. Making a composite part that passes mechanical tests does not verify that the modeling equations or operator thinking are correct and can be trusted to make predictions. 

Mechanical testing of the three-step cure specimens indicated that no sacrifice in properties resulted from the modification of the process cycle. The retainment of mechanical properties (transverse strength and modulus) coupled with the reduction in dimensionless curvature for the three-step cure cycles investigated provides another suitable cure cycle modification for reduction of residual stresses in composite materials. Overall processing time has not been increased beyond that specified in the MRC cycle. Thus, with no increase in process time and comparable mechanical properties, the residual stresses have been reduced by more than 20 percent in comparison to the MRC cycle baseline data. 

---