Definition and Characteristics of Ultimate Tensile Strength
– Ultimate tensile strength is the maximum stress a material can withstand before breaking.
– It is an intensive property that does not depend on the size of the test specimen.
– Brittle materials have ultimate tensile strength close to the yield point, while ductile materials can have higher ultimate tensile strength.
– The highest point on the stress-strain curve is the ultimate tensile strength.
– Compression has a similar equivalent point called compressive strength.
– Ductile metals experience plastic deformation and necking before fracture.
– After the yield point, strain hardening occurs and the stress increases with increasing strain.
– Necking causes a reversal of the stress-strain curve, with the ultimate tensile strength at the maximum stress point.
– Ultimate tensile strength is not used in the design of ductile static members, but is used for quality control and material identification.
– It is important for designing brittle materials that have no yield point.
Testing and Application of Ultimate Tensile Strength
– Tensile testing involves pulling a small sample until it breaks.
– Indentation hardness can be correlated with tensile strength in some metals.
– This correlation allows for nondestructive testing of bulk metal deliveries using portable equipment.
– Tensile testing is widely used in quality assurance in metalworking industries.
– It provides valuable information about the strength and properties of materials.
– Ultimate tensile strength is important in designing brittle materials.
– It is not a design consideration for ductile members, which use yield stress instead.
– Ultimate tensile strength is used for quality control and material identification.
– It helps determine the suitability of materials for specific applications.
– Tensile strengths are tabulated for common materials like alloys, ceramics, plastics, etc.
Typical Tensile Strengths of Different Materials
– Steel, structural ASTM A36 has a yield strength of 250 MPa and ultimate tensile strength of 400-550 MPa.
– Aluminium alloy 6061-T6 has a yield strength of 241 MPa and ultimate tensile strength of 300 MPa.
– Carbon fiber (Toray T1100G) is one of the strongest human-made fibers with an ultimate tensile strength of 7,000 MPa.
– Glass has a density of 2.53 g/cm³ and E-Glass has an ultimate tensile strength of 1,500 MPa for laminates.
– Spider silk from the Darwins bark spider has an ultimate tensile strength of 1,652 MPa.
– Wood, pine (parallel to grain): 104-121 MPa
– Bone (limb): 130 MPa
– Limpet teeth (goethite whisker nanocomposite): 4,900-6,500 MPa
– Spider silk (highly variable): Approximately 1,000 MPa
– Human hair (varies by ethnicity and treatments): Varies
– Nylon, molded, 6PLA/6M: 75-85 MPa
– Nylon fiber, drawn: 900 MPa
– Epoxy adhesive: 12-30 MPa
– Rubber: Varies
– Polybenzoxazole (Zylon): 2,700 MPa
– Iron (pure mono-crystal): 7.874 g/cm3
– Stainless steel, grade 302: Varies
– Aluminum: Varies
– Titanium: Varies
– Copper: Varies
– Carbon fiber composites: 1,200 MPa
– Carbon nanotube composites: 11,000-63,000 MPa
– Boron nitride nanotube: 33,000 MPa
– High-strength carbon nanotube film: 9,600 MPa
– Glass fiber-reinforced plastic (fiberglass): Varies
– Silicon, monocrystalline (m-Si): 7,000 MPa
– Ultra-pure silica glass fiber-optic strands: 4,100 MPa
– Sapphire (Al2O3): 400 MPa at 25°C, 275 MPa at 500°C, 345 MPa at 1,000°C
– Diamond: 1,600 MPa
– Graphene: Intrinsic 130,000 MPa; engineering 50,000-60,000 MPa
Importance of Ultimate Tensile Strength in Design and Applications
– Ultimate tensile strength is important in designing brittle materials.
– It is not a design consideration for ductile members, which use yield stress instead.
– Ultimate tensile strength is used for quality control and material identification.
– It helps determine the suitability of materials for specific applications.
– Tensile strengths are tabulated for common materials like alloys, ceramics, plastics, etc.
Advanced Materials with High Ultimate Tensile Strength
– Carbon fiber (Toray T1100G): 7,000 MPa
– Spider silk (Darwins bark spider): 1,652 MPa
– Polybenzoxazole (Zylon): 2,700 MPa
– Carbon nanotube composites: 11,000-63,000 MPa
– Boron nitride nanotube: 33,000 MPa
– High-strength carbon nanotube film: 9,600 MPa
– Silicon, monocrystalline (m-Si): 7,000 MPa
– Ultra-pure silica glass fiber-optic strands: 4,100 MPa
– Sapphire (Al2O3): 400 MPa at 25°C, 275 MPa at 500°C, 345 MPa at 1,000°C
– Diamond: 1,600 MPa
– Graphene: Intrinsic 130,000 MPa; engineering 50,000-60,000 MPaSources: https://en.wikipedia.org/wiki/Ultimate_tensile_strength
