Thiokol Corporation Research Articles

Shear Lap-Joint Testing with Rubber Substrate

Abstract A test method has been developed and demonstrated for the determination of shear strength in a lap joint with rubber-like material as a substrate. A testing fixture used a stiffened aluminum substrate with a load-transferring lip, combined with a clamp, that restrained the lateral movement of the rubber. This fixture successfully produced shear-type failures on two back-to-back single lap-joint specimens. The design of the fixture was based on the near-incompressible nature of the rubber materials. The experimental part of the task included two phases: a pathfinder test series; and the actual data generation test series. The former phase involved testing concept development, test fixture design and modification, optimization of test specimen configuration, and failure mode demonstration. This phase was conducted using specimens fabricated in-house by the Mechanics and Materials Technology Center at The Aerospace Corporation. In the second phase, actual shear failure data were generated using specimens that were machined from panels fabricated by the vendor, Elkton Division, Tactical Operations of the Thiokol Corporation. Linear elastic finite element analyses were performed to assist in the optimization of test parameters. The results identified optimal dimensions for lap-joint length, transverse groove width, and bracket lip width for the specimen and fixture configuration. Sixteen tests were done on specimens machined from vendor-supplied carbon phenolic/Epon EA 934 NA/ethylene propylene diene monomer (EPDM) panels. The average failure stresses were 4.46, 3.39, and 3.32 MPa (0.56, 0.43, and 0.42 ksi) for the 7.62, 10.16, and 12.70-mm (0.3, 0.4, and 0.5 in.) long lap-joints. Some of the failures were initiated inside the adhesive whereas other failures occurred between the adhesive and the substrate. This test method should be considered as a viable technique in determining shear strength of bond line with rubber-like material as a substrate. More refinement, however, is needed before an optimal test fixture design can be reached.

Dissolution study of BAMO/AMMO thermoplastic elastomer for the recycling and recovery of energetic materials

This study involves the characterization and dissolution of a thermoplastic elastomer copolymer used as binder in the new generation of energetic materials. The thermoplastic binder is an oxetane based elastomer manufactured by Thiokol Corporation. Since the binder encapsulates other components in an energetic material formulation, its controlled dissolution is crucial to the recovery and recycle of all the energetic material ingredients. The polymeric binder was found to be highly soluble in ethyl acetate and THF. The dissolution rate data obtained under well defined flow dynamics was satisfactorily correlated with the film model. External mass transfer resistance was found to be generally important but became negligible for Reynolds numbers above 6.0×104. The mass transfer coefficients calculated on the basis of the film model were found to be an Arrhenius function of temperature. The activation energy for the dissolution rates was estimated to be 4.8 kcal/mol.

Catastrophic events, contagion, and stock market efficiency: the case of the space shuttle challenger

AbstractThis study examines the stock returns experienced by NASA contractors associated with the Space Shuttle Challenger explosion. Because of the extensive public interest in the explosion and the intensive and stirring news coverage, this event is a candidate for an irrational market response such as a selloff, a panic, or a contagion effect. The market evidence shows that on the day of the explosion, there was a significantly negative average abnormal return on the stock of NASA contractors. Any contagion effect was limited to a very narrow set of NASA contractors who received more than 5% of their 1995 revenues from NASA. Furthermore, the market was able to identify within days after the event that the single firm most likely to be affected by the event was Morton Thiokol Corporation.

In Situ Measurement of Hydrochloric Acid in Rocket Exhaust Clouds Using a Remotely Piloted Aircraft

Abstract An instrumentation system employing an RPV (remotely piloted vehicle) platform was developed for temporally and spatially resolved air pollution measurements, and was used to measure the evolution of gas-phase HC1 in exhaust clouds from a solid rocket motor firing and fuel pit burns. A thermistor and a sensitive (ppmv-level), rapid-response (<0.1 sec) infrared absorption sensor for HC1 were mounted in a flow channel in the RPV, permitting concentration and temperature measurements to be made in the cloud on a several-meter scale. The RPV system was flown in a series of field tests at Thiokol Corporation’s Elkton, MD division to evaluate the HC1 content of the exhaust products of a new Mg-based fuel formulation. Measurements were made in the clouds from Al-based and Mg-based solid fuel pit burns and a Mg-fueled motor firing over periods of several minutes. Elevated temperatures and HC1 concentrations were found to be temporally correlated with video images of the particulate cloud. Cl originating ...

Space Shuttle redesigned solid rocket booster structural dynamic liftoff predictions and correlations

A transient analysis was performed that predicted and correlated the structural static and dynamic behavior of the Space Shuttle redesigned solid-rocket booster (RSRB) during the first redesigned flight, STS-26R, liftoff. A finite element model of the RSRB was analyzed to predict the accelerations, strains, and displacements measured by developmental flight instrumentation that was bonded to the motor during flight. A detailed RSRB finite element model was developed and correlated for use in analyzing the booster behavior during liftoff loading conditions. This finite element model used MSC/NASTRAN superelement techniques to model all components of the RSRB in detail. The accuracy of the assembled RSRB global model was validated by correlation to static fire and other tests performed by Thiokol Corporation. Mode acceleration transient analysis methods were applied to this validated RSRB global model to predict RSRB structural behavior using the actual loading conditions measured during liftoff. Essential information describing the analytical model and techniques used, correlation of the predicted vs measured RSRB behavior, and conclusion are presented in this study.

Method for making a composite component using a transverse tape: Youngkeit D.C. (Thiokol Corporation, Ogden, UT, USA) US Pat 4 938 824 (3 July 1990)

Method for making a composite component using a transverse tape: Youngkeit D.C. (Thiokol Corporation, Ogden, UT, USA) US Pat 4 938 824 (3 July 1990)

Sylvania's gte products problem stoppers: #1 employee involvement team

Anyone doubting the dedication of North American workers to total quality and continuous improvement on the job should have witnessed the 1992 National Team Excellence Competition. Competition was stiff and included such world-renowned companies as AT&T, Florida Power and Light, Thiokol Corporation, British Columbia Telecom, Atlantic Electric, Harris Corp., Weirton Steel, Rockwell Houstin Operations, Diamond Star Motors, United Technologies, Principal Financial Services, and Weyerhauser Co. The winner of the 1992 Association for Quality and Participation'S National Team Excellence Competition was a nine-person work team called the Problem Stoppers from Sylvania Lighting in York, Pennsylvania. The Problem Stoppers won for eliminating glass waste at York by recycling it in the plant, which not only saved the company about $142,000, but also proved to be an outstanding example of total quality environmental management and responsibility. This article details their award-winning efforts.

Method of coating fiber materials with resin: Youngkeit, D. (Thiokol Corporation, Chicago, IL, USA) US Pat 4 530 855 (23 July 1985)

Method of coating fiber materials with resin: Youngkeit, D. (Thiokol Corporation, Chicago, IL, USA) US Pat 4 530 855 (23 July 1985)

Bend-Brittle and Shatter Points of Rubberlike Materials

Abstract Within the past two years the performance of rubberlike compositions at low temperatures has become important. A number of tests have been devised to measure the loss of rubberlike properties of many of these compositions. As the temperature is lowered, the first indication of the loss of rubberlike properties is hardening of the material. As the temperature is lowered further, the material continues to stiffen and harden to a point where it becomes quite inflexible; bending or striking with a solid object then causes breaking or shattering, due to the brittleness of the material. Up to this time the temperature at which breaking occurs has been called the “brittle point” of the material, with no distinction between the temperature at which breaking occurs on bending and the temperature at which breaking occurs on striking with a sharp blow from a solid object. It would be easy to assume that the two points occur at the same temperature. Koch tested the brittle point of elastic materials by measuring the bend stress with a micrometer gauge placed in the center of the specimen that was supported at each end. By observing the distortion caused by weights, the elastic modulus could be measured to the breaking point, which occurred at a definite temperature. This bend-brittle temperature was called the “high elasticity” temperature by Houwink and the “elasticity” temperature by Whitby. An apparatus was developed by the Thiokol Corporation for determining the flexibility of rubberlike materials at low temperatures. The samples are mounted between two plates and bent by turning a crank. The apparatus was designed so that the distance between the plates can be varied. The temperature of breaking was called the “brittle point”.

Low Temperature Flexing Apparatus

Abstract For the past ten months, Sub-Committee V of SAE-ASTM Technical Committee A on Automotive Rubber has been working on the standardization of synthetic rubber specifications. Insofar as possible, methods of tests have followed ASTM procedures. ASTM has no recommended procedure for measuring the low temperature flexibility of synthetic rubber. This committee, after careful consideration, has recommended the use of a modification of the Thiokol Corporation's freeze test. This method of testing for low temperature flexibility has been incorporated into a number of recent Aeronautical Material Standards Specifications covering synthetic rubber. The modified test uses the same apparatus as that used in the Thiokol Corporation's Laboratory, or slight modifications of this. Because of the interest in this apparatus, a short description of it is here given.