General Properties of Materials PDF

CE 133 – CONSTRUCTION MATERIALS AND TESTING LECTURE/LABORATORY College of Engineering GENERAL PROPERTIES OF MATERIALS ENGR. ROMEL B. SAN INSTRUCTOR DIEGO JR. GENERAL PROPERTIES OF MATERIALS Buildin...

CE 133 – CONSTRUCTION MATERIALS AND TESTING LECTURE/LABORATORY College of Engineering GENERAL PROPERTIES OF MATERIALS ENGR. ROMEL B. SAN INSTRUCTOR DIEGO JR. GENERAL PROPERTIES OF MATERIALS Building or Construction materials are engineering materials subjected to loads and are expected to respond through the process of deformation to the actions of the loading. The prope ies of building materials are the basic attributes required for sustainability during load application, which include strength, stress/strain, modulus (elastic and shear), ductility, creep, durability, shrinkage, permeability, etc. CMT LECTURE/LABORATORY College of Engineering GENERAL PROPERTIES OF MATERIALS Knowledge of these prope ies would provide information on the extent of load tolerance necessa for the construction material's active pe ormance, according to engineering standards, codes, and speci cations. CMT LECTURE/LABORATORY College of Engineering CLASSIFICATION OF PROPERTIESMATERIAL PHYSICAL PROPERTY A material undergoes transition under the in uence of temperature and pressure, and these changes are physical in nature because their molecules remain intact. [Density, speci c gravity, porosity, water absorption, etc…] CMT LECTURE/LABORATORY College of Engineering MECHANICAL PROPERTY It is the prope y of a material that opposes the deformation or breakdown of material in the presence of external forces or load. [tensile strength, compressive strength, rigidity, hardness, creep, fatigue, etc…] CMT LECTURE/LABORATORY College of Engineering THERMAL PROPERTY It is the prope y of a material that is related to its conductivity of heat. These are the prope ies that are exhibited by a material when heat is passed through it. CMT LECTURE/LABORATORY College of Engineering CHEMICAL PROPERTY It is any of a material’s prope ies that becomes evident during, or after, a chemical reaction; that is, any quality that can be established only by changing a substance’s chemical identity. Chemical prope ies cannot be determined just by viewing or touching the substance; the substance’s internal structure must be a ected greatly for its chemical prope ies to be investigated. [resistance to acids, alkalis, brine, and oxidation] CMT LECTURE/LABORATORY College of Engineering ECONOMIC PROPERTY These are the cost-saving characteristics. CMT LECTURE/LABORATORY College of Engineering AESTHETIC PROPERTY The qualities that make a product attractive to look at or pleasing to experience. [color, su ace smoothness, the re ection of light, etc…] CMT LECTURE/LABORATORY College of Engineering MECHANICAL PROPERTIES MECHANICAL PROPERTIES It is impo ant to understand the mechanical prope ies of the material. The mechanical prope ies of a material are those that a ect the mechanical strength and ability of a material to be molded in a suitable shape. CMT LECTURE/LABORATORY College of Engineering STRENGTH It is the ability of a material to resist the externally applied forces without breaking or yielding. The internal resistance o ered by a pa to an externally applied force is called stress. CMT LECTURE/LABORATORY College of Engineering TOUGHNESS It is the ability of a material to absorb energy and get plastically deformed without fracturing. Its numerical value is determined by the amount of energy per unit volume. Its unit is Joule/ m3. The value of the toughness of a material can be determined by the stress-strain characteristics of a material. For good toughness, materials should have good strength as well as ductility. For example: brittle materials, having good strength but limited ductility are not tough enough. Conversely, materials having good ductility, but low strength are also not tough enough. Therefore, to be tough, material should be capable of withstanding both high stress and strain. CMT LECTURE/LABORATORY College of Engineering HARDNESS It is the ability of a material to resist permanent shape change due to external stress. There are various measures of hardness which are: Scratch Hardness, Indentation Hardness, and Rebound Hardness. CMT LECTURE/LABORATORY College of Engineering HARDNESS 1.Scratch Hardness Scratch Hardness is the ability of materials to oppose the scratches to the outer su ace layer due to external force. 2.Indentation Hardness It is the ability of materials to oppose the dent due to the punch of external hard and sharp objects. 3.Rebound Hardness Rebound hardness is also called dynamic hardness. It is determined by the height of the “bounce” of a diamond-tipped hammer dropped from a xed height on the material. CMT LECTURE/LABORATORY College of Engineering HARDENABILITY It is the ability of a material to attain hardness by heat treatment processing. It is determined by the depth up to which the material becomes hard. The SI unit of hardenability is a meter (like length). The hardenability of material is inversely propo ional to the weldability of material. CMT LECTURE/LABORATORY College of Engineering BRITTLENESS The Brittleness of a material indicates how easily it gets fractured when it is subjected to a force or load. When a brittle material is subjected to stress it obse es much less energy and fractures without signi cant strain. Brittleness is converse to the ductility of the material. The brittleness of the material is temperature-dependent. Some metals which are ductile at normal temperatures become brittle at low temperatures. CMT LECTURE/LABORATORY College of Engineering MALLEABILITY Malleability is a prope y of solid materials that indicates how easily a material gets deformed under compressive stress. Malleability is often categorized by the ability of a material to be formed in the form of a thin sheet by hammering or rolling. This mechanical prope y is an aspect of the plasticity of the material. The malleability of material is temperature dependent. With the rise in temperature, the malleability of material increases. CMT LECTURE/LABORATORY College of Engineering DUCTILITY Ductility is a prope y of a solid material which indicates how easily a material gets deformed under tensile stress. Ductility is often categorized by the ability of a material to get stretched into a wire by pulling or drawing. This mechanical prope y is also an aspect of the plasticity of material and is temperature- dependent. With the rise in temperature, the ductility of material increases. CMT LECTURE/LABORATORY College of Engineering CREEP AND SLIP Creep is the prope y of a material which indicates the tendency of material to move slowly and deform permanently under the in uence of external mechanical stress. It results due to long time exposure to large external mechanical stress within the limit of yielding. Creep is more severe in materials that are subjected to heat for a long time. Slip-in material is a plane with a high density of atoms. CMT LECTURE/LABORATORY College of Engineering RESILIENCE Resilience is the ability of a material to absorb the energy when it is deformed elastically by applying stress and releasing the energy when stress is removed. Proof resilience is de ned as the maximum energy that can be absorbed without permanent deformation. The modulus of resilience is de ned as the maximum energy that can be absorbed per unit volume without permanent deformation. It can be determined by integrating3the stress-strain cu e from zero to the elastic limit. Its unit is joule/m. CMT LECTURE/LABORATORY College of Engineering FATIGUE Fatigue is the weakening of material caused by the repeated loading of the material. When a material is subjected to cyclic loading and loading greater than a ce ain threshold value but much below the strength of the material (ultimate tensile strength limit or yield stress limit), microscopic cracks begin to form at grain boundaries and inte aces. Eventually, the crack reaches a critical size. This crack propagates suddenly, and the structure gets fractured. The shape of the structure a ects the fatigue ve much. Square holes and sharp corners lead to elevated stresses where the fatigue crack initiates. CMT LECTURE/LABORATORY College of Engineering STIFFNESS Sti ness is the ability of a material to resist deformation under stress. The modulus of elasticity is the measure of sti ness. CMT LECTURE/LABORATORY College of Engineering ELASTICITY It is the prope y of a material to regain its original shape after deformation when the external forces are removed. This prope y is desirable for materials used in tools and machines. It may be noted that steel is more elastic than rubber. CMT LECTURE/LABORATORY College of Engineering PLASTICITY Plasticity is a prope y of a material that retains the deformation produced under load permanently. This prope y of the material is necessa for forgings, stamping images on coins, and ornamental work. CMT LECTURE/LABORATORY College of Engineering