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Dr. HABEEB HATTAB HABEEB Office: BN-Block, Level-3, Room-088 Ext. No.: 7292 Lecturer: Dr. HABEEB ALANI.

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Presentation on theme: "Dr. HABEEB HATTAB HABEEB Office: BN-Block, Level-3, Room-088 Ext. No.: 7292 Lecturer: Dr. HABEEB ALANI."— Presentation transcript:

1 Dr. HABEEB HATTAB HABEEB Office: BN-Block, Level-3, Room-088 Email: Ext. No.: 7292 Lecturer: Dr. HABEEB ALANI

2 Manufacturing Processes University TENAGA National College Of Engineering Mechanical Department Academic Year - 2009 Lecture Note Lecturer: Dr. HABEEB ALANI

3 Nature and Properties of Materials Lecturer: Dr. HABEEB ALANI

4 - Classification of Materials Used in Manufacturing - Engineering Properties of Material - Composites and New Materials Nature and Properties of Materials Lecturer: Dr. HABEEB ALANI

5 Materials Metallic Non-Metallic Ferrous Non-Ferrous Organic Inorganic - CLASSIFICATION OF MATERIALS Lecturer: Dr. HABEEB ALANI

6 Ferrous Aluminum Titanium Non-Ferrous MATERIALS Gray Cast Iron Malleable Iron Steel Zinc METALLIC Lecturer: Dr. HABEEB ALANI

7 Organic Glass Ceramic Inorganic MATERIALS Leather Wood Rubber Fused silica NON-METALLIC Lecturer: Dr. HABEEB ALANI

8 MATERIALS Ferrous and Non-Ferrous alloys Non-ferrous materials are very important because they are alloyed with ferrous materials special properties can be obtained. Example: Good cutting properties can be added to tool steel by alloying it with molybdenum or vanadium. Lecturer: Dr. HABEEB ALANI

9 MATERIALS Non-metallic materials are classified as inorganic if they do not contain organic cells or carbon compounds. See Table 2.1&2.2 (Metals and Non-Metals) All materials have their importance in manufacturing. In automobile industry we can find all types of materials in a car (fig. next slide):- Ferrous → Steel (Body), Non- Ferrous → Aluminum, organic → Rubber, Inorganic → Glass. Lecturer: Dr. HABEEB ALANI



12 MATERIALS Glass -Petroleum -Wood -Ceramic -Animal product -Nickel SteelPlastic Lead RubberCompositeAluminum Lecturer: Dr. HABEEB ALANI

13 According to service characteristic and cost a designer (Material Engineer or R&D Engineer) can suggest a compromise of choice between metallic and non-metallic, and between organic and inorganic. Example: To reduce weight and improve some specific properties, manufacturers are used to designing ADVANCED COMPOSITES MATERIALS (Fiber Reinforced Plastics) These material are composed at least two material: 1. Fiber (fiber class, carbon, Graphite) 2. Binder or matrix (Thermoplastic, Polymer) Lecturer: Dr. HABEEB ALANI

14 Engineering properties Tensile strength - ENGINEERING PROPERTIES OF MATERIALS Shear Compressive Torsion strength Ductility Creep Notch sensitivity Lecturer: Dr. HABEEB ALANI

15 Engineering properties Tensile strength Strength - The amount of ultimate and yield strength in psi a material can withstand. Strength - The ability of a materials to resist deformation when external forces are applied. Lecturer: Dr. HABEEB ALANI

16 Engineering properties Specimen Test: A specimen is tested by pulling its two ends. Then the tensile strength is determined by finding:- 1. Stress = Force per unit area. = N/m 2 (Pa) or lb/in 2 (psi) Lecturer: Dr. HABEEB ALANI

17 Engineering properties 2.Strain = units of in/in Strain (ε) =Change in length over the original length. ε = 3. Modulus of Elasticity = Stress / Strain = σ/ε A measure of Elasticity Determines the slope of the stress / strain curve where it is a straight line. L 1 - L L Lecturer: Dr. HABEEB ALANI

18 Normalize Applied-Force to Supporting Area TENSILE Stress,  Area, A F t F t  F t A o original area before loading –Engineering Stress Units → N/m 2 (Pa) or lb/in 2 (psi) Stress,  Lecturer: Dr. HABEEB ALANI

19 ¾ inch ½ inch 8 ½ inches L - Failure Zone Gripping Zone Tensile specimen Lecturer: Dr. HABEEB ALANI



22 Point a: - Represents the Elastic Limit. After this point with more force a Permanente deformation takes place. (The curve is no longer straight line) Point b: - At this point the material Yield Strength is determined. Lecturer: Dr. HABEEB ALANI

23 Point c: - At this point the material Ultimate Strength is determined. Point d: - A fracture will occur after Maximum Deformation. Lecturer: Dr. HABEEB ALANI

24 Tensile – applied loads “pull” the sample Forces and Responses Lecturer: Dr. HABEEB ALANI

25 Simple tension: cable Simple shear: drive shaft Ski lift A o = cross sectional Area (when unloaded) FF M M A o 2R F s A c Common States Of Stress Lecturer: Dr. HABEEB ALANI

26 Common States Of Stress Cont.. Simple COMPRESSION: A o Balanced Rock Bridge Lecturer: Dr. HABEEB ALANI

27 Shear strength - There is no universal standard used for evaluating shear or torsion characteristic - Shear can be determined from hand- books. - Usually Shear Strength = 50% of tensile strength Lecturer: Dr. HABEEB ALANI

28 Shear strength - Torsional Strength = 75% of tensile strength - Shear Stress G ୪ ୪ – Displacement angle (Shear angle or shear strain) Lecturer: Dr. HABEEB ALANI

29 Shear strength G – Shear modules or the modulus of rigidity. G = (3 / 8) E or G = E / 2 (1 + ୪ ) Lecturer: Dr. HABEEB ALANI

30 Page-23 Lecturer: Dr. HABEEB ALANI

31 Compressive Strength It is easily determined for brittle materials (Cast iron) that will fractures when a sufficient load is applied. Compressive strength for cast iron = (3 to 4) tensile strength. Because of this properties of some,material which fracture easily we should use a factor of safety FS, Lecturer: Dr. HABEEB ALANI

32 Compressive Strength FS = σ actual / σ allowable Recommended values of FS = 1 to 3 High values of FS are used for unreliable material or when severe load is applied Low values of FS are used for reliable materials (steel). Lecturer: Dr. HABEEB ALANI

33 Ductility This property enable the material to be bent, drawn, stretched, formed or permanently distorted without rupture (aluminum, structural steel). Ductility for cast iron is minimum (a brittle material) Tensile test is used to evaluate ductility: Percentage of elongation= [(L f -L)/L]x100 Lecturer: Dr. HABEEB ALANI

34 Ductility L- Original length, Lf- New length after fracture Lecturer: Dr. HABEEB ALANI

35 Ductility ductility: Ability of a material to deform under tension without rupture. Two ductility parameters may be obtain from the tensile test: 1- Relative elongation - ratio between the increase of the specimen length before its rupture and its original length: Lecturer: Dr. HABEEB ALANI

36 Ductility ε = (Lm– L0) / L0 Where Lm– maximum specimen length. 2-Relative reduction of area – ratio between the decrease of the specimen cross-section area before its rupture and its original cross-section area: ψ= (S0– Smin) / S0 Where Smin– minimum specimen cross- section area. Lecturer: Dr. HABEEB ALANI

37 Creep And Notch sensitivity Creep: Is a permanent deformation resulting from the loading of members over a long period of time. High Temperature creep lead to: Failure of loaded units such as (High- pressure steam piping) Lecturer: Dr. HABEEB ALANI

38 Creep And Notch sensitivity Elongating caused by creep will occure below the yeild strength of the material. Heat treatment, grain size, and chemical composition appreciably affect Creep strength Lecturer: Dr. HABEEB ALANI

39 Creep And Notch sensitivity Notch sensitivity On the other hand is a measure of the ease with which a crack progresses through a material from an existing notch, crack, or sharp corner. Lecturer: Dr. HABEEB ALANI

40 Next Lecture: Foundry Lecturer: Dr. HABEEB ALANI


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