Mechanical properties of neat polymer matrix materials and their unidirectional carbon fiber-reinforced composites

The mechanical properties of two neat resin systems for use in carbon fiber epoxy composites were characterized. This included tensile and shear stiffness and strengths, coefficients of thermal and moisture expansion, and fracture toughness. Tests were conducted on specimens in the dry and moisture-saturated states, at temperatures of 23, 82 and 121 C. The neat resins tested were American Cyanamid 1806 and Union Carbide ERX-4901B(MPDA). Results were compared to previously tested neat resins. Four unidirectional carbon fiber reinforced composites were mechanically characterized. Axial and transverse tension and in-plane shear strengths and stiffness were measured, as well as transverse coefficients of thermal and moisture expansion. Tests were conducted on dry specimens only at 23 and 100 C. The materials tested were AS4/3502, AS6/5245-C, T300/BP907, and C6000/1806 unidirectional composites. Scanning electron microscopic examination of fracture surfaces was performed to permit the correlation of observed failure modes with the environmental test conditions

Static tensile and tensile creep testing of five ceramic fibers at elevated temperatures

Static tensile and tensile creep testing of five ceramic fibers at elevated temperature was performed. J.P. Stevens, Co., Astroquartz 9288 glass fiber, Nippon Carbon, Ltd., (Dow Corning) Nicalon NLM-102 silicon carbide fiber, and 3M Company Nextel 312, 380, and 480 alumina/silica/boria fibers were supplied in unsized tows. Single fibers were separated from the tows and tested in static tension and tensile creep. Elevated test temperatures ranged from 400 to 1300 C and varied for each fiber. Room temperature static tension was also performed. Computer software was written to reduce all single fiber test data into engineering constants using ASTM Standard Test Method D3379-75 as a reference. A high temperature furnace was designed and built to perform the single fiber elevated temperature testing up to 1300 C. A computerized single fiber creep apparatus was designed and constructed to perform four fiber creep tests simultaneously at temperatures up to 1300 C. Computer software was written to acquire and reduce all creep data

Waste heat management in the electric power industry : issues of energy conservation and station operation under environmental constraints

Over the past three years, the Energy Laboratory, in cooperation with the R.M. Parsons Laboratory for Water Resources and Hydrodynamics at M.I.T. has been under contract with DOE/ECT to study various water and waste heat management issues associated with the choice of cooling systems for large steam-electric power plants. The purpose of this report is to summarize the major findings to-date of this study. In addition, an introduction or background section proceeds the summary so that the results can be better integrated into the larger picture of water and waste heat management.Over the past three years, the Energy Laboratory, in cooperation with the R.M. Parsons Laboratory for Water Resources and Hydrodynamics at M.I.T. has been under contract with DOE/ECT to study various water and waste heat management issues associated with the choice of cooling systems for large steam-electric power plants. The purpose of this report is to summarize the major findings to-date of this study. In addition, an introduction or background section proceeds the summary so that the results can be better integrated into the larger picture of water and waste heat management

Mechanical properties of several neat polymer matrix materials and unidirectional carbon fiber-reinforced composites

The mechanical and physical properties of three neat matrix materials, i.e., PEEK (polyetheretherketone) thermoplastic, Hexcel F155 rubber-toughened epoxy and Hercules 8551-7 rubber-toughened epoxy, were experimentally determined. Twelve unidirectional carbon fiber composites, incorporating matrix materials characterized in this or earlier studies (with one exception; the PISO(sub 2)-TPI matrix itself was not characterized), were also tested. These composite systems included AS4/2220-1, AS4/2220-3, T500/R914, IM6/HX1504, T300/4901A (MDA), T700/4901A (MDA), T300/4901B (MPDA), T700/4901B (MPDA), APC2 (AS4/PEEK, ICI), APC2 (AS4/PEEK, Langley Research Center), AS4/8551-7, and AS4/PISO(sub 2)-TPI. For the neat matrix materials, the tensile, shear, fracture toughness, coefficient of thermal expansion, and coefficient of moisture expansion properties were measured as a function of both temperature and moisture content. For the unidirectional composites, axial and transverse tensile, longitudinal shear, coefficient of thermal expansion, and coefficient of moisture expansion properties were determined, at room temperature and 100 C

Double Cantilever Beam Fracture Toughness Testing of Several Composite Materials

Double-cantilever beam fracture toughness tests were performed by the Composite Materials Research Group on several different unidirectional composite materials provided by NASA Langley Research Center. The composite materials consisted of Hercules IM-7 carbon fiber and various matrix resin formulations. Multiple formulations of four different families of matrix resins were tested: LaRC - ITPI, LaRC - IA, RPT46T, and RP67/RP55. Report presents the materials tested and pertinent details supplied by NASA. For each material, three replicate specimens were tested. Multiple crack extensions were performed on each replicate

Double Cantilever Beam and End Notched Flexure Fracture Toughness Testing of Two Composite Materials

Two different unidirectional composite materials were provided by NASA Langley Research Center and tested by the Composite Materials Research Group within the Department of Mechanical Engineering at the University of Wyoming. Double cantilever beam and end notched flexure tests were performed to measure the mode I (crack opening) and mode II (sliding or shear) interlaminar fracture toughness of the two materials. The two composites consisted of IM7 carbon fiber combined with either RP46 resin toughened with special formulation of LaRC IA resin, known as JJS1356; or PES chain extended thermoplastic resin known as JJS1361. Double Cantilever Beam Specimen Configuration and Test Methods As received from NASA, the test specimens were nominally 0.5 inch wide, 6 inches long, and 0.2 inch thick. A 1 inch long Kapton insert at the midplane of one end of the specimen (placed during laminate fabrication) facilitated crack initiation and extension. It was noted that the specimens provided were smaller than the nominal 1.5 inch wide, 9.0 inch long configuration specified. Similarly, the Kapton inserts were of greater length than those in the present specimens. Hence, the data below should not be compared directly to those generated with the referenced methods. No preconditioning was performed on the specimens prior to testing. In general, the methodology was used for the present work. Crack opening loads were introduced to the specimens via piano hinges attached to the main specimen faces at a single end of each specimen. Hinges were bolted to the specimens using the technique presented. The cracks were extended a small distance from the end of the Kapton insert prior to testing. Just before precracking, the sides of the specimens were coated with water-soluble typewriter correction fluid to aid in crack visualization. Scribe marks were then made in the coating at half-inch intervals

Strain energy release rate as a function of temperature and preloading history utilizing the edge delamination fatique test method

Static laminate and tension-tension fatigue tests of IM7/8551-7 composite materials was performed. The Edge Delamination Test (EDT) was utilized to evaluate the temperature and preloading history effect on the critical strain energy release rate. Static and fatigue testing was performed at room temperature and 180 F (82 C). Three preloading schemes were used to precondition fatigue test specimens prior to performing the normal tension-tension fatigue EDT testing. Computer software was written to perform all fatigue testing while monitoring the dynamic modulus to detect the onset of delamination and record the test information for later retrieval and reduction

The Effect of Glucose on Neutrophilic Phagocytosis

Samples of blood were obtained from thirty healthy young adult males (Loma Linda University School of Dentistry), and contaminated with bacteria. Varying concentrations of pure glucose were added to this mixture to observe the effect of the glucose on in vitro neutrophilic phagocytosis. As the glucose levels increased a statistically significant suppression was noted in the ability of the neutrophilic leukocytes to engulf Staphylococcus epidermidis. It was not possible, however, to predict the degree of suppression for any particular level of glucose added nor is it possible to state that suppression will occur in any one individual. Two methods of phagocytic index determinations were used. The first recorded the percentage of neutrophils that had phagocytized and the second counted the number of bacteria per phagocyte. Statistically no difference was noted between the two methods

Diet of Juvenile Alabama Shad (Alosa alabamae) in Two Northern Gulf of Mexico Drainages

Understanding food-web ecology is valuable to conservation by linking interactions of multiple species together and illustrating the functionality of trophic exchange. Alosa alabamae (Alabama Shad), an anadromous species, reproduces in northern Gulf of Mexico drainages from February through May, and for this study, the Pascagoula and Apalachicola rivers were chosen to sample juvenile Alabama Shad. The age-0 fish mature within these rivers and have the potential to impact the food web of the systems in which maturation occurs. The focus was to determine if diet changes as Alabama Shad mature, and to identify diet differences between drainages. Diets of Alabama Shad (SL) consisted primarily of a dark, almost black material labeled as unidentifiable organics. while larger Alabama Shad. \u3e50 mm SL, fed almost exclusively on insects. Many groups of aquatic and terrestrial insects were found in the stomachs of this species. Alabama Shad diets also differed among drainages, with the Apalachicola River being dominated by terrestrial insects, and the Pascagoula River having both terrestrial and aquatic insects. Diet and trophic placement of Alabama Shad may allow managers to understand the importance of this fish within its natal rivers

Static tensile and tensile creep testing of four boron nitride coated ceramic fibers at elevated temperatures

Six types of uncoated ceramic fibers were static tensile and tensile creep tested at various elevated temperatures. Three types of boron nitride coated fibers were also tested. Room temperature static tensile tests were initially performed on all fibers, at gage lengths of 1, 2, and 4 inches, to determine the magnitude of end effects from the gripping system used. Tests at one elevated temperature, at gage lengths of 8 and 10 inches, were also conducted, to determine end effects at elevated temperatures. Fiber cross sectional shapes and areas were determined using scanning electron microscopy. Creep testing was typically performed for 4 hours, in an air atmosphere