ميكانيكا المواد
DESCRIPTION
ميكانيكا المواد. Mechanics of Materials. Strength of Materials. Lec . 1. Grading توزيع الدرجات HW 10% الواجبات Attendance 10% الحضور 1 st MT 15% يوم 27 شعبان 2 nd MT 15% يوم 19 رمضان Final 50% يوم 17 شوال. - PowerPoint PPT PresentationTRANSCRIPT
المواد ميكانيكا
Mechanics of Materials
Strength of Materials
Lec. 1
2
Course IDCourse NameHoursCourse Type
803323Mechanics of Materials 3, 0, 3Required Core Course
InstructorOfficeExtensionEmail
Mohammed A AlsabbanG1153, Building [email protected]
Office HoursMonday11:00am-12:00 noon
Grading الدرجات توزيعHW 10% الواجباتAttendance 10% الحضور1st MT 15% شعبان 27يوم 2nd MT 15% رمضان 19يوم Final 50% شوال 17يوم
3
4
تقديم Introduction
• Mechanics of Materials is the study of the internal effect of external forces applied to structural member. Stress, strain, deformation deflection, torsion, flexure, shear diagram, and moment diagram, topics covered by this subject. تأثير دراسةواالنفعال االجهاد داخليا، المادة على الخارجية القوىالقص واالنثناء، االلتواء الحجم، وتغير والتشوه
بيانيا وابرازهم والعزوم• Materials المتوفرة المواد دراسة• Stiffness (deformation characteristics) المادة مقاومة
الخارجية القوى تأثير تحت والشكل الحجم لتغير• Stability (of load-carrying members) األعضاء اتزان
المواد خصائص Characteristics ofدراسةMaterials
• Laboratory معامل في تتم• Specimens قياسية عينات بأخذ• Test قياسية اختبارات واجراء
• Behaviorورصد
• Physical Characteristics الخصائص وتحديدالميكانيكية
Method of Sectionsالمقاطع طريقة
• Internal resistance of a body داخلية مقاومة• Forces within to balance external forces توازن داخلية قوى
الخارجية القوى• Stable body at rest is in equilibrium جسم الساكن الجسممستقر
• Arbitrary section (suggested where?) اختياري مقطع• Body divided into parts أجزاء الى الجسم يقطع• Parts must also be in equilibrium في المقطوعة االجزاء
اتزان حالة• External forces are balanced by the internal forces القوى
الخارجية القوى مع تتوازن الداخلية• Free Body Diagram (FBD) تحليله في يساعد للنظام حر رسم
Stressاإلجهاد • Stress : Intensity of Force, or force divided by area
[N/m2], called [Pascal] مساحة وحدة على القوة شدة االجهاد
• Perpendicular and Parallel resolution of stress للسطح موازي أو عمودي
) عمودي ) رأسي Normalاجهاد
Stress σ
Normal Stress σ• Tension force produces tensile stresses to lengthen the
member. العضو من ويطيل شد اجهاد عنها ينتج الشد قوة• Compressive force produces compressive stresses to
shorten the member. ضغط اجهاد عنها ينتج الضغط قوةالعضو طول من ينقص
القص Shear Stress τاجهاد• Parallel to plane للسطح موازي
The most general state of stress acting on an element
Equilibriumاالتزان • If the body as a whole is in equilibrium, any
part of it must also be in equilibrium. الجسممتزن منه مقطوع جزء أي المتزن
• ∑ F external = ∑ F internal
• تساوي الخارجية القوى مجموعالداخلية القوى مجموع
Units (SI)Strength of Materials
Lec. 1
• Force [ Newton, N]
•Area [m2 or mm2]
•Stress [Pascal, Pa]
•Pa = Pascal =
15
• MPa = Mega Pascal =
The most general state of stress acting on an element
Axial Load and Normal Stress
• Stress is maximum when plane of cut is perpendicular to force.
• Axial loads produces uniaxial stress• Loads acting through the centeroid of the
cross-sectional area produces uniformly distributed stress
Average Shearing Stress
• Stresses in the plane parallel to the applied force
• Assuming uniformly distributed stress• The average shearing stress is
Critical Section
• Section that have the minimum cross-sectional area and the greatest axial force
• Maximum Stress occurs at the critical section
Equilibrium Equations
• For 2-D (x-y plane) it is reduced to:
Determinate VS Indeterminate
• Depending on the number of the unknown reactions a problem may be identified as:
DeterminateOr
Indeterminate• Ways to solve problems will differ accordingly
Factor of Safety• For design purposes ultimate strength can NOT be
applied directly and a factor of safety is introduced.
Reasons:• Not sure about magnitude of applied force• Assumed Uniformity of material is no exactly true.• Corrosion• Plastic deformation under sustained loads• Cyclic Loading and Fatigue• Residual Stresses
Review
Support Reactions
ReviewEquilibrium:
Internal Resultant Loadings
Review
Coplanar Loadings
Review
Examples
Homework Problems
Review
Average normal stress
Review
Average shear stress
Pure Shear
Homework Problems
Review
Allowable Stress
Review
Design of Simple Connections
Homework Problems