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One point of note is that the yield region is not as cleanly defined as BCD is in the image (although most books have it that way). In reality the yield region looks like The following image is one from many actual measurement that I took years ago (its Force Displacement). You can see the jagged yield region after the elastic region. The point is that the ...


5

Point "C" is the "offset yield point" or "proof stress" as described below. The yield strength or yield stress is a material property and is the stress corresponding to the yield point at which the material begins to deform plastically. The yield strength is often used to determine the maximum allowable load in a mechanical ...


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Yes; from B to C it is behaving elastically AND plastically. A small amount of plastic strain ( less than 0.2%) is mixed with elastic strain.


3

The stress is not uniform near the grip because there is a biaxial state of stress. There is the axial force the compression force from the grips. That is the reason that if the Cross-section was uniform the failure would start from the grip. the mental image is the following: If you have a ballon that you apply force from one end, and at the same time ...


2

Efficiency is a relative term in comparing structures built using different materials and technologies. For prestressed concrete, it is most justifiable to compare it to its next kin - cast-in-place concrete. The efficiencies mainly lie in two aspects - load carrying capacity and cost. 1) Load carrying capacity: i) For the same size and span length of a beam,...


2

The rebars just for the sake of being embedded in the concrete do not work! It has to be stretched to work. Hooks law, $ \ F=Kdx, \quad K = E*A$ That's why we place the rebars on the bottom not near the center of the beam, to give them elongation. So a lot of good concrete that could be used for compression has to crack open stretching with rebar while ...


2

As far as I know, the enlarged part is used to grip the specimen. The fillet and smaller cross-section area is where the necking happens and that smaller cross-section is designed to avoid necking on the grip. I think the failure does not happen at the end. If its completely axial load, the whole specimen will elongate and become thin, then the failure would ...


2

One does not want the rupture in the grips; that makes elongation and reduction of area measurements very difficult. Also, notch sensitive materials will rupture in the grip area unless the the grips are significantly larger cross-section than the gage length. For notch sensitive materials even the shoulders must have a long gradual taper to avoid shoulder ...


2

Rubber is a hyperelastic material. It doesn't fall under the typical Ductile or Brittle categories. Percentage elongation and percentage reduction in length or area basically refers to permanent elongation or reduction, after the material has undergone any sort of plasticity (i.e. surpassing the yield strength of the material). If it experiences elongations ...


2

Generally what happens is that if when the load is removed (quasi statically) the material will return in a path which is parallel to the elastic region. Eg. for load up to E and F the following behaviour is observed. Notice that the slope of the red arrows is identical to the slope of OA section (region up to proportionality point). hysteresis If the load ...


2

Summary: There is increasing plastic behavior and decreasing elastic behavior as the sample is strained from B to C. The transition is caused by random grain orientations and variable resolved shear stress. With respect, the other answers generally have the right idea, but are missing the important meso-scale mechanism for why there is a non-linear shape ...


1

Rather than getting hung up on the words, consider their usage. The authors' definition may only make sense in a specific context that that they were trying to convey. Ductile was about the ability to draw a material into a wire. The word or its roots may even preceed quantification of structural properties, but that's somewhat irrelevant. What is ...


1

Question 1: Elastic recovery will always take place until the material surpasses the Ultimate Tensile Strength (UTS) of it. This means that when ever you load a material and if it doesn't surpass its UTS, then it won't fracture but will be longer in length (in a Tensile loading) than its initial length when unloaded. Between B and C, the material is on the ...


1

As the name of the subject, "Statics", suggests, the beam and every piece of the segment (AF & FD), that is imaginarily separated from the beam, must stay static in its own system. In structural terms, it means the beam and the segments must remain in "structural equilibrium", either in the global scene/system, or the local scene/...


1

Concrete performs best (and more consistently) when loaded in compression. (Putting concrete in tension is not good practice). When a beam is pre-stressed essentially the rebars are acting as a spring that compresses the entire beam. Thus more of the material is in a state that can perform in a useful manner. On the other hand, the rebars also perform better ...


1

The utility company and the local government are different entities, each has its own priorities and budgets, and the life cycle of the road and utility lines usually differs, such makes coordination extremely difficult except for new development. Direct bury the powerlines underground poses a hazard for the latter roadside construction activities, routine ...


1

You have left out the most important data of the concrete - grade 25 concrete (M25), which has a compressive strength ($f_c'$) of, approximately, 3600 psi (or 3625 psi to be close to exact). I assume you are an engineer, from here you shall be able to determine its elastic (Young's) modulus, maximum tensile strength prior to crack, and the allowable stresses ...


1

I) Regarding your first question of "why can we make this assumption that the components of the truss experience axial forces only, not the bending moment", well we have to dig into the reason we select a truss rather than a solid beam to bridge two support points at the first place. For a space with fixed span length but no restriction on depth, ...


1

When modelling district heating network, I came across this figure showing recommended pipe diameters with respect to the flow velocity (of hot water). I hope it illustrates how maximum flow velocity should be considered w.r.t. pipe parameters. To evaluate the effect of the chosen design guideline, it has been differentiated between four design guidelines. ...


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