Bài giảng Vật liệu học - Chương 4: Tính chất cơ cung cấp cho người học các khái niệm về tính chất cơ, biến dạng đàn hồi, đường công ứng suất và biến dạng (stress strain curves),... Mời các bạn cùng tham khảo nội dung chi tiết.
Chương Tính chất Khái niệm • VL thường chịu tác dụng lực sử dụng • Tính chất VL xác định biểu VL tác dụng ngoại lực • Đáp ứng VL với ngoại lực phụ thuộc vào: Loại liên kết Sự xếp nguyên tử cấu trúc VL Loại số lượng khuyết tật • Tính tốn: Giá trị lực Biến dạng VL hàm theo lực, thời gian, nhiệt độ,… • Tính chất thể qua phép thử học (theo tiêu chuẩn: ASTM (American Society for Testing and Materials), ISO (International Organization for Standardization)…) CuuDuongThanCong.com https://fb.com/tailieudientucntt CuuDuongThanCong.com https://fb.com/tailieudientucntt CuuDuongThanCong.com https://fb.com/tailieudientucntt CuuDuongThanCong.com https://fb.com/tailieudientucntt Ứng suất=Lực / diện tích Ứng suất kéo • Tensile stress, s: Ứng suất trượt • Shear stress, t: Ft s Ao original area before loading CuuDuongThanCong.com Stress has units: N/m2 or lb/in2 https://fb.com/tailieudientucntt Độ biến dạng • Tensile strain: /2 wo • Shear strain: L/2 /2 /2 - = tan • Lateral strain: Lo /2 L/2 Strain is always dimensionless /2 /2 CuuDuongThanCong.com https://fb.com/tailieudientucntt Stress (s) for tension and compression F s Ao Strain (e) for tension and compression Tensile load Compressive load Shear stress Fs t Ao Shear strain = tan CuuDuongThanCong.com Torsional deformation angle of twist, f https://fb.com/tailieudientucntt Mô đun đàn hồi E (Young’s modulus, modulus of elasticity) Định luật Hooke (Hooke's Law): s=Ee CuuDuongThanCong.com https://fb.com/tailieudientucntt ỨNG SUẤT TRONG CÁC TRƯỜNG HỢP THỰC TẾ • Simple tension: cable F s Ao • Simple shear: drive shaft Ski lift (photo courtesy P.M Anderson) Fs t Ao Note: t = M/Ac CuuDuongThanCong.com https://fb.com/tailieudientucntt • Simple compression: Ao Canyon Bridge, Los Alamos, NM (photo courtesy P.M Anderson) Balanced Rock, Arches National Park (photo courtesy P.M Anderson) Note: compressive structure member (s < here) 10 CuuDuongThanCong.com https://fb.com/tailieudientucntt 29 CuuDuongThanCong.com https://fb.com/tailieudientucntt 30 CuuDuongThanCong.com https://fb.com/tailieudientucntt 31 CuuDuongThanCong.com https://fb.com/tailieudientucntt 32 CuuDuongThanCong.com https://fb.com/tailieudientucntt 33 CuuDuongThanCong.com https://fb.com/tailieudientucntt 34 CuuDuongThanCong.com https://fb.com/tailieudientucntt 35 CuuDuongThanCong.com https://fb.com/tailieudientucntt 36 CuuDuongThanCong.com https://fb.com/tailieudientucntt 37 CuuDuongThanCong.com https://fb.com/tailieudientucntt 38 CuuDuongThanCong.com https://fb.com/tailieudientucntt 39 CuuDuongThanCong.com https://fb.com/tailieudientucntt 40 CuuDuongThanCong.com https://fb.com/tailieudientucntt 41 CuuDuongThanCong.com https://fb.com/tailieudientucntt 42 CuuDuongThanCong.com https://fb.com/tailieudientucntt 43 CuuDuongThanCong.com https://fb.com/tailieudientucntt ... elastic linear elastic plastic https://fb.com/tailieudientucntt 14 ĐƯỜNG CONG ỨNG SUẤT-BIẾN DẠNG (STRESS-STRAIN CURVES) • Typical tensile specimen • Typical tensile test machine • Other types... compressive structure member (s < here) 10 CuuDuongThanCong.com https://fb.com/tailieudientucntt • Bi-axial tension: Pressurized tank (photo courtesy P.M Anderson) Fish under water s > sz > CuuDuongThanCong.com... https://fb.com/tailieudientucntt Độ biến dạng • Tensile strain: /2 wo • Shear strain: L/2 /2 /2 - = tan • Lateral strain: Lo /2 L/2 Strain is always dimensionless /2 /2 CuuDuongThanCong.com