The central point of the area of any shape is shown as its centroid or the centre of the area. The centre of area is concerned witht only the shape. While, the centre of gravity is concerned with solids which have length, breadth, thickness & mass. these for ingredient. Very abstract.
try this:
the centre of gravity is the centre of teh mass of a body and can be described as the imaginary point at which the whole weight of the body may be considered to act. the centre of gravity of a body is a fixed point at the centre of its mass. This pint does not change, regardless of the position adopted by the body.
Tuesday, May 17, 2011
Toughness
Toughness is the property which enables a metal to withstand shock loading or impact. Metal which have poor qualities of toughness are said to be brittle. Cast iron is a brittle metal and has poor resistance to shock load such as hammer blows.
Hardness is the property which enables a material to resist abrasion and indentation. Like the glass of your watch.
Low carbon steel 0.25%
Medium carbon steel 0.25 - 0.65 %
High carbon steel 0.65 - 1.4 % carbon
Hardness is the property which enables a material to resist abrasion and indentation. Like the glass of your watch.
Low carbon steel 0.25%
Medium carbon steel 0.25 - 0.65 %
High carbon steel 0.65 - 1.4 % carbon
Modulus of Elasticity
18/5/2011
I've already left the world of blogging for a while and today i am coming back. I'd guess i better get warm up.
Modulus of elasticity is, E = stress/strain
A material with a high elasticity meaning that it is stiff and hence it deforms relatively little under load. So, quite abstract isn't it. i'll take one example from badminton racket. A stiff racket meaning when you hit it it bend little while a flexible racket when you hit it, it will bend more.
So if you are using carbonex which is stiff shaft, that mean it is stiffer that the steel gonna hurt you shoulder more.
E for steel is 205 000 N/mm2
So when you have a steel you pull it and pull it then you release it, it will go back to its on shape. That is because it is still in the elastic range. So next you try again with a greater force, you pull it untill you can feel the warmness of the steel when you release it, it won't go back to its original length, because all the energy have been lost in friction when the steel crystal have dragged over each other. This is the plastic range.
I've already left the world of blogging for a while and today i am coming back. I'd guess i better get warm up.
Modulus of elasticity is, E = stress/strain
A material with a high elasticity meaning that it is stiff and hence it deforms relatively little under load. So, quite abstract isn't it. i'll take one example from badminton racket. A stiff racket meaning when you hit it it bend little while a flexible racket when you hit it, it will bend more.
So if you are using carbonex which is stiff shaft, that mean it is stiffer that the steel gonna hurt you shoulder more.
E for steel is 205 000 N/mm2
So when you have a steel you pull it and pull it then you release it, it will go back to its on shape. That is because it is still in the elastic range. So next you try again with a greater force, you pull it untill you can feel the warmness of the steel when you release it, it won't go back to its original length, because all the energy have been lost in friction when the steel crystal have dragged over each other. This is the plastic range.
Tuesday, May 11, 2010
ASD n LRFD method
In simplest practical language, Allowable stress Design (ASD) is about reducing the strength capability of the structure. say reduce 40 percent. Still confused, say you can lift 20kg but we reduce 40%, you only allowed to carry 20kg x 0.6 = 12kg. Why we do this? because there are many factors out there that you cannot control and anticipate. For example, the standard of material, the human error in calculating loadings, error of contractor and many more.
How about LRFD? LRFD is all about is all about load combination. In stead of reducing the capacity of the structural you maintain it but you increase the loading for 30%, 50%.
So we can argue which one is good. They all have their strength and specific function in specific circumstances. Just rember this, ASD give conservative result if the ratio of Live Load to Dead Load is less than 1 to 3. On the other hand, LRFD method give conservative design is the Live Load to Dead Load is more than 1 to 3.
How about LRFD? LRFD is all about is all about load combination. In stead of reducing the capacity of the structural you maintain it but you increase the loading for 30%, 50%.
So we can argue which one is good. They all have their strength and specific function in specific circumstances. Just rember this, ASD give conservative result if the ratio of Live Load to Dead Load is less than 1 to 3. On the other hand, LRFD method give conservative design is the Live Load to Dead Load is more than 1 to 3.
Monday, March 29, 2010
Feelin sick
I just recall i have slight headache on Sunday, and yesterday wasn't feeling top. But i've thought that it is the moodiness caused by the boring. I went over to basketball court to shake it off. And today i woke up with a slight headache. Went back for lunch and felt the heating and my body temperature rise, yeah i thought must be the body working to kill the virus, bacteria, or something else yeah.
Time of this i would expect a help for example, a warm water and a panadol. It would be helpful.
Today i have learned about the wave load. Basically, for wave load there are two kind: operational wave load and storm wave load.
Let me explain about the operational load first, for the operational load it is the average of 30 days.
So you will take the highest 10 wave and get the average. Way by, for the storm waves it is 100 years period. It order to get the structural dynamics effect of the wave we need to check first whether the structural building frequency similar more than 3 sec. Hardly, remember it.
On the other hand, as for the wind load effect of the wind load to flare boom structure. You probably can divide the area in to 3 area and assign the loading to each of the centroid of the structure.
Last but not learn, learn and forget couple of thing like ball valve, pressure valve...the memory is quite hazy so better that way may be.
Time of this i would expect a help for example, a warm water and a panadol. It would be helpful.
Today i have learned about the wave load. Basically, for wave load there are two kind: operational wave load and storm wave load.
Let me explain about the operational load first, for the operational load it is the average of 30 days.
So you will take the highest 10 wave and get the average. Way by, for the storm waves it is 100 years period. It order to get the structural dynamics effect of the wave we need to check first whether the structural building frequency similar more than 3 sec. Hardly, remember it.
On the other hand, as for the wind load effect of the wind load to flare boom structure. You probably can divide the area in to 3 area and assign the loading to each of the centroid of the structure.
Last but not learn, learn and forget couple of thing like ball valve, pressure valve...the memory is quite hazy so better that way may be.
Wednesday, March 24, 2010
New words of the day
Invoice: is a document that specified the quantity, prices that buyer need pay the seller. That my simple view and understanding of it hahahaha. From engineering terms of view it is Bill of Quantities(BQ) huhuhuh.
when you don't know what you know it is called stupid
when you don't know what you don't know it is called stupid arrogance
when you know what you know it is called knowledgeable
when you know and admit what you don't know it is called Wisdom.
My simple sharing of what i know i know.
when you don't know what you know it is called stupid
when you don't know what you don't know it is called stupid arrogance
when you know what you know it is called knowledgeable
when you know and admit what you don't know it is called Wisdom.
My simple sharing of what i know i know.
To study or not to study
Yesterday i've read about the Project Management. Actually i am intrigued and have the desire to join. But, i have a lot of limitations in terms of economics benefits, social benefits, personal benefits and potential benefits i can foresee. However from the horizon i am looking at it is not very desirable in the practical sense. Perhaps my horizon is deflected by what i've see and block by some stumbling block like a big mountain blocking the beautiful sight and view.
Pro
-economic potential,
-diversity of potential income
-learn extra knowledge
-networking with different people from difference field
Cons
-will burn a hole in my pocket as it is very expensive
-do not know the potential of this application of this knowledge.
Pro
-economic potential,
-diversity of potential income
-learn extra knowledge
-networking with different people from difference field
Cons
-will burn a hole in my pocket as it is very expensive
-do not know the potential of this application of this knowledge.
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