Data and conclusions from tests on small screws
The integrity of many mechanical assemblies and electrical components depends on small threaded fasteners. The design standards for small (less than {1/4} inch in diameter) screws made of stainless steel are not as well developed as those for larger sizes of high strength steels. The typical design approach is based on the application of static design principals. Steady state accelerations are applied to the component or assembly and sufficient screws are installed in mounting hardware for attachment to the next assembly. These design principals have been used successfully for years in a wide variety of applications. As the parts requiring small screws have continued to decrease in size, some design requirements include greater thread depths and adherence to strict interpretation of the governing thread standards. These design requirements have their origins in the lack of adequate definitions and standards for designs using small threaded fasteners. These design practices have led to significant problems in manufacturing parts with small threaded fasteners by requiring thread depths to four and more diameters of engagement while maintaining thread heights (radial engagement) of 75 percent throughout the thread interfaces. A test program was developed to address questions regarding design and manufacturing issues involving small threaded fasteners which included tensile strength, length of engagement needed to achieve the full strengths of the screws, and verification of the static design principals in dynamic conditions. This paper summarizes the initial results obtained to date from this test program and describes the work-in-progress on the dynamic tests with their related static tests. 2 refs., 4 figs., 4 tabs.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- Sponsoring Organization:
- DOE/DP
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 7030355
- Report Number(s):
- SAND-90-0534C; CONF-9006122--3; ON: DE90007500
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360103 -- Metals & Alloys-- Mechanical Properties
42 ENGINEERING
420500* -- Engineering-- Materials Testing
ALLOYS
ALUMINIUM
DATA PROCESSING
ELEMENTS
FAILURE MODE ANALYSIS
FASTENERS
FREQUENCY ANALYSIS
FUNCTIONS
HIGH ALLOY STEELS
IMPACT SHOCK
INSTALLATION
IRON ALLOYS
IRON BASE ALLOYS
MACHINING
MANUFACTURING
MATERIALS TESTING
MATHEMATICAL MODELS
MEASURING METHODS
MECHANICAL PROPERTIES
MECHANICAL VIBRATIONS
METALS
PERFORMANCE TESTING
PROCESSING
STAINLESS STEELS
STANDARDS
STATISTICAL MODELS
STEELS
STRENGTH FUNCTIONS
STRESS ANALYSIS
SYSTEM FAILURE ANALYSIS
SYSTEMS ANALYSIS
TEMPERATURE EFFECTS
TENSILE PROPERTIES
TESTING
VARIATIONS