SolidWORKS Academy

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Post by Interesting Engineering.

How to sketch a car - Technical Drawing

For this tutorial I will show the different steps I take in drawing a realistic looking car. I chose to draw an american classic, the Corvette. This tutorial will apply to any car though because for the most part, they are all the same. The key to drawing a car that will pop off the page is having a good balance of lights, midtones, and darks along with clean, sharp edges. As with most of my graphite drawings, I am using Derwent Graphic Pencils and Fabriano Artistico Bright White Watercolor Paper . I am also using mechanical pencils for small details. 

I buy all of my supplies from Blick Art Materials . Buying your stuff from that link helps me keep adding to this site. Let's get started. 

Step 1 - Proportions are critical in a technical drawing so I have gridded my outline using 1 inch squares. Gridding consists of placing a grid over your reference picture and on your drawing paper and then transfering the image square by square until you've attained an outline. DO NOT use a hard graphite (ie. 5H, 2H, H) for your grid. If you do you will have a nightmare on your hands later when you are shading. Harder graphites dent the paper, creating tiny grooves. When you go to shade over these grooves, they will not accept graphite and will appear white. Use a softer graphite like a B for your grid. Don't say I didn't warn you :) 
 

Step 2 - As with all of my drawings I am working left to right, top to bottom (just like reading). I am starting on the front of the car and the front wheel. For the wheel I am laying down my darkest tones first with a 7B pencil. These dark tones will give me a reference when deciding how dark to go with everything else on the wheel. The wheels can be very time consuming if you want them to turn out well. They are very small and have lots of details. This one rim alone will take me about an hour.
 

Step 3 - I add the midtones and lighter tones to the wheel with a 2H for lights and a 3B for mids. These tones are what makes the wheel appear to shine. As with any metal surface, the wheels have brilliant highlights. I always leave these highlights alone so that they are the tone of the paper. So with my midtones and light tones around these brilliant highlights, they appear to shine. This process is called negative drawing and can be explained further by clicking on the link. At this point, the wheel is basically done. When we shade the tires later, these highlights will really start to shine.
 

Step 4 - With the front wheel finished, I move onto the front fender area. For the darker bottom part of the fender I use a 3B pencil. The lighter top area I am using a 2H. A car finish is typically very smooth so I am blending the body with blending stumps. When working on the body, I am comparing tones to those on the wheel. I'm also erasing grid lines so they don't interfere with my shading. 
 

Step 5 - I go back and work on the tire. Pay close attention to the way the tire looks. There will be some diffuse (duller) highlights or possibly even some brilliant ones if the tire is wet or has tireshine on it. You can see how the rim looks a lot shinier now that we have some darker tones around the negative space. You can make the wheels look as shiny or as dull as you'd like by adjusting the surrounding tones. I will probably go back and darken a lot to make the highlights pop even more. After the tire, I go back to the body with a 3B pencil and blending stumps. You can see how I am just working one square inch at a time. Working this way makes you focus more on details than the drawing as a whole.
 

Step 6 - I continue working on the body and move up to the window. The tones of everything showing through the window will be slightly muted compared to the rest of the car. So I make the steering wheel and dashboard a little bit lighter. If the window had been opened or tinted this would not be the case though. I used a 2H pencil for the lighter parts of the window, a B pencil for the darker areas and a blending stump to finish it off.
 

Step 7 - Keep working on the door paying close attention to your reference photo. There are very subtle tone changes in the lighter areas. I'm still using a 2H for lights and a 3B for the darks. 
 

Step 8 - Since our light source is coming from the front of the car, the rearview mirror is reflected off of the body. This reflection will be darker than the mirror itself. Just pay close attention to your reference photo when rendering details like this. After that is done I continue working on the body. The car is starting to take shape now. As mentioned earlier, just take it nice and slow working one area at a time. 
 

Step 9 - I continue working on the body of the Corvette. The top of the car will be a lighter area, considering the light source so I use a 2H on it. I finish the area along the rear wheelwell using a 3B and blending stumps. Then I move onto the middle area of the car, shading with both 2H and B pencils. The doorhandle is one of the darkest area so I use a 7B pencil on it.
 

Step 10 - I start working on the back windshield. I used a 3B on this area. A shadow underneath the car comes next. The shadow grounds the car and makes it look like it's actually sitting on a surface rather than hovering in space. I use a 3B mechanical pencil on this area pressing fairly hard. Mechanical pencils work better on large dark areas than woodcased pencils. They are sharper and are able to push the graphite deep into the fibres of the paper.
 

Step 11 - Now I am working on the rear wheel. This will be exactly like before but I will go through it again since the wheels are very important. I am laying down my darkest areas first with a 7B. Make sure your pencil is sharp so that your edges are nice and clean.
 

Step 12 - Next I am adding the midtones to the wheel. Break up the wheel into different sections and focus on one small area at a time. I am working in between the spokes. You can see now that with the midtones in place, the wheel is starting to look 3 dimensional. In this case, light tones suggest an area that is closest to the viewer. So with these midtones and darks laid down, the spokes are the lightest and appear to pop out at us.
 

Step 13 - The lighter tones are added to the wheel using a 2H pencil. Now the rim is complete. It will begin to shine more when we get the dark tire tones around it. I am a little tired of focussing on the wheel area so I work some more on the body. I'm still using a 3B for darks and 2H for lights. 
 

Step 14 - I begin to work on the rear of the car, using 3B for darks. Considering where the light source is coming from (the front), the lighter areas will be darker than the lights on rest of the car. This is because the rear is not exposed to the light. So I am using a B pencil on these areas.
 

Step 15 - I go back to the tire area. I darkened in the tire using a 3B pencil. Then I went back and added small details. With the darker tones around the wheel, you can see how it begins to shine and resemble chrome. I continue working on the rear of the car, still using 3B.
 

Step 16 - Paying close attention to details I move on, working more on the rear of the car until it is done. For my darkest areas I used a 3B pencil. The drawing is complete. Now you can go back and add more details if you'd like. I always have a look at the drawing from a few steps back to see if something doesn't look right.
 



All of my tutorials are free, I don't ask for anything in return. I make them because I enjoy talking art and teaching others. They do take me quite a while to put together, a lot of work goes into them. If you have enjoyed or benefitted from this tutorial all I ask is that you help promote it. You can do this by submitting to social networking sites, linking, blogging, or posting links on forums. Promoting my tutorials is a huge help!! 

How to handle your studies effectively?

1) Spend time everyday working on the subject matter

Devoting time periods each day for study means that frequent learning advancements will occur organically. Learning almost any subject (engineering, mathematics, economics, psychology) can be compared to learning languages – if you don’t regularly “use” it, then you’ll lose it.  Spending regular time reading, writing, thinking and researching each day will also get you into good organisational habits.

2) Understand via questioning

When revising material, ask yourself questions that facilitate understanding.   For example, if you are reading a section within a book, then ask yourself:  “What are the main points / ideas of this section?”;  “What is the author trying to tell me?”;   “Why does the conclusion follow from the premise?”  This will develop critical reasoning and enable you to summarise the section in your own words and style.

3) Concentrate for no longer than 50 minutes

Giving yourself regular breaks is an essential part of effective studying, as a break will freshen the mind and relieve stress.  My advice is to study for no longer than 50 minutes before taking a 10 minute break.  The break might involve a drink or snack to keep your energy up.

4) Consider simple cases first

Many people learn a new idea most effectively by starting with simple and introductory examples, rather than general and abstract theories. Get your confidence up by trying to understand a basic case of a more general idea.  By moving from the simple to the more abstract, you’ll master different levels of knowledge and detail, logically progressing to comprehending the ideas deeply.

5) Examine past test papers

If a subject’s syllabus does not change much from year to year, then it is a good idea to locate past test papers for the subject and to study them carefully. Complete as many as you can. What kinds of questions have been asked in previous years?  Not only will this familiarise yourself with subject-matter, but it will also give you a guide on what questions teachers have found important over the years, plus it will inform you on what level of details in answers / solutions are required.

6) Engage with the material to help the learning process

A positive attitude can go a long way to break down mental barriers to learning.  Try to stay positive when studying seemingly tedious or dry material.  If certain content seems irrelevant or downright boring then ask yourself, or your teacher, how the ideas can be motivated and contextualised.

7) Don’t give up: You can do it!!

If you persevere with sustained and strategic study habits, building confidence along the way, then you’ll SUCCEED in your examinations.  You can do it!!

By: Dr. Chris Tisdell

MIT FInal Year Projects

Nano-Set'14 -- Engineering Competition

The present energy crisis and future energy demands have triggered a significant interest in the development of energy sources and efficient power generators to cater the needs across the globe. Therefore, it is the need of the day to take initiative in this area.

COMSATS Institute of Information Technology, Lahore is going to organize a three day International conference on the impact of nanoscience on energy technologies (NanoSET-2014) from 18-20 March 2014.

The purpose of this conference is to bring together ideas and solutions from all over the world where researchers, engineers, academics as well as industrial professionals from diverse backgrounds will share their thoughts for further development in building renewable sources of energy. The conference will cover areas like Clean Energy, Solar, Hydro, Wind, Biomass, Fuel Cell, batteries and energy utilization by means of environmental and economically sustainable technologies.

To deliberate on the energy technologies and to share their achievements in this area, experts from the international Universities especially; from KTH (Sweden), Delaware (USA), Manchester (UK), UCL (UK), St. Andrews (UK), Edinburgh (UK), Aalto (Finland), Tianjin (China), Tsinghua (China), Hebei university (China), and Lancaster University (UK) are expected to participate. The organizers/participants of the conference would be able to provide solutions based on the need of the 21st century after having free and frank deliberations on the energy issues. It can also help to make Energy Policies for the country.

Stress Analysis of different combinations of POPSICLES

What the heat is???

Heat has always been perceived to be something that produces in us a sensation of warmth, and one would think that the nature of the heat is one of the first things understood by mankind. Actually the mankind is looking in wrong direction. The nature of heat is very different from what we are thinking about, from millions of years. It is quite amazing to know that the thing which we are considering the simple one, and we are claiming ourselves to be the true interpreters of it, is still unknown to us until the beginning of middle of nineteenth century.

It is the middle of nineteenth century, when we had a true physical understanding of the nature of heat due to the development of kinetic theory. Actually the kinetic theory treats the molecules of a substance as tiny balls that are in motion and thus possess kinetic energy. These tiny balls (molecules) are capable of rotating about their own axis, vibrating about their mean position, and translation from one place to another. These movements arise due to intermolecular interactions, external disturbances and any other driving force. These movements, especially the translational one, are what we called heat. And the warmth we sense is actually the effect of these movements and nothing else. We are considering this warmth as a substance, and that is totally wrong. But there is another surprise here. In the mid of nineteenth century although we are able to relate that warmth with the movement of molecules but still we are not looking in true direction. At that time a French chemist Antoine Lavoisier proposed caloric theory. He says that although heat is generated due to molecular movements but it flows like a fluid like substance that is massless, colorless, odorless and tasteless substance that can be poured from one substance to another. Note that he is thinking the heat as generated by the movement of molecules rather than saying that heat itself is the movement of molecules. He says that when heat (which he called caloric) is added to a body its temperature increased; and when caloric was removed from the body, its temperature decreased. When a body could not contain any more caloric, much the same way as when a glass of water could not dissolve any more salt or sugar, the body was said to be saturated with caloric. And you will be surprised to know that the words like saturated liquid and saturated vapors which we are using today are based on this interpretation of caloric theory. So that is how the words saturated liquid and saturated vapor emerge. But there is another surprise here. Recent experiments shows that the thermal conductivities of the same material at same operating conditions are not same on NANO scale. But our recent concepts about heat suggests that it must be same. But a great deviation is experienced when two specimens of same material, one on large scale and other on NANO scale are tested for thermal conductivities. These results astonished the scientists, leaving room to again think about that what heat is??

Source: Heat and Mass transfer by Cengel ….

Research By: Engr. Ammar Aziz   

The World's first Seismograph

Actually seismograph is a word devoted to the measurement of earthquakes precisely. As far as earthquake is concerned, it is one of the most disastrous hazards faced by humans in their history, and still we are experiencing it.

As we all know that it is scientifically proved fact that the mountains are actually designed by ALLAH to control the earthquakes on earth. But there is a question here. Why earthquakes hit mostly the regions populated with mountains? The answer to that question is simple. Because most of the patients are found to be in a doctor’s clinic!!!

The history of china tells us that it experienced many earthquakes in ancient times due to presence of mountainous region. So to deal with that they strongly feel that they must have something to deal with earthquakes. Unfortunately in the modern era, we are still unable to control the earthquake but at that time a wonderful thing happened. A Chinese guy, Zhang Heng invented the world’s first ever seismograph for the prediction of earthquake. Let us see how it works. Actually this seismograph is based on very simple but intelligent principles of vibration. Ok let us discuss it:

The material chosen for this seismograph is fine cast bronze. This seismograph had a diameter of eight ‘chi’, and was shaped like a wine jar. Keep in mind that ‘chi’ is the unit of length used by Chinese for the measurement of length in ancient times. Calculations show that one chi is almost equal to 0.237 meters. As in this case the diameter of wine jar is eight chi, it implies that its diameter is almost 1.896 meters. So now it is easy to imagine the size of that seismograph. Inside this wine jar, Zhang Heng made it possible to hang a mass with some string (you can say it a pendulum). He clamped the string at the one end with a hole in the top lid of the wine jar. And at the second end he attached a mass. After adjusting the pendulum within the jar he surrounded the pendulum within the jar by eight levers pointing in eight directions. These levers are aligned in such a way that the angle between them is 45 degrees. So that the eight levers are covering the 360 degrees. He projected the some length of levers outside the wine jar and here he attached the crafted dragon mouths. So there are 8 dragons total on the outside of jar. Below each dragon he precisely aligned the crafted toads. Zhang Heng then place the balls within the mouth of each dragon. Now let us see how this arrangement works. A strong earthquake in any direction would tilt the pendulum inside the jar in that direction. The mass of pendulum strikes the lever in that direction. Due to which this lever transforms the momentum from the mass of the pendulum to corresponding ball within the mouth of the dragon. This ball fell in the mouth of the toad with clanging sound. So two purposes are achieved simultaneously with this invention. It enabled the personnel to determine the time of earthquake by hearing the clanging sound of ball. And it enabled the personnel to determine the direction of occurrence of earthquake by determining that which ball among the eight fell into the mouth of toad. It is quite amazing to know that how intelligently people are thinking at that time.

Conceived and Complied by: Engr. Ammar Aziz

Elasto-Hydrodynamic lubrication (EHL)

Summary

In this article the summary of the developments about Elasto-hydrodynamic lubrication (EHL) is given. Two types; starved EHL and grease EHL are highlighted in this article. EHL is the type of lubrication that occurs in lubricated contra formal contacts where the elastic deformation of the lubricated surfaces has a substantial influence on the thickness of the lubricating film. EHL is very important in order to produce less expensive, more efficient and environment friendly products. The history of EHL started when Reynolds derived the differential equation describing the pressure distribution and load carrying capacity of lubricating films for journal bearings. Later on many scientists proposed many procedures to explain full film lubrication and finally the concept of amplitude reduction opened the possibilities to apply EHL theory to real surface roughness by means of fast Fourier transform methodology.

This paper describes the relationship of lubricant’s density with temperature and its pressure. It is to be noted that density variation with respect to temperature change is not considered in this paper. Density variation with pressure is nearly linear at low pressure. This paper also gives a brief review about the numerical method that are used to solve the mathematical problems regarding EHL. But due to high computing costs and solution convergence issues engineer tries to find the analytical solutions to these equations. The calculation of reduced pressure, dimensionless pressure and thickness of the thin film is done by considering simple assumptions regarding lubricant and applying Reynolds equation. This method does not provide the information about the exact thickness of film and also unable to identify its location. To overcome this problem, Greenwood introduced another assumption that the pressure and its distribution can be approximated by considering the elastic solution. To evaluate the outlet pressure he referred the concepts of fracture mechanics. After that paper describes some techniques which are used to measure the thickness of the film. This can be done by using high resolution and slow speed cameras. In this technique, it is necessary that one of meeting surfaces must be transparent.

As we are reviewing the Elasto-Hydrodynamic lubrication theory, so it is important to analyze it from different aspects. One of the most important factor is 'Inlet Shear heating'. When a bearing operates, then the lubricant is squeezed due to load supported by bearing. But the journal within the bearing not only rotates but also slides to some extent. Due to this sliding action some of the fluid is rejected back to its earlier position, at the point of contact. This rejected fluid slides over the incoming fluid, due to which heat is generated within the lubricant due to shear effect. This shear heating effect must be considered for proper review of EHL theory.

Actually classical EHL theory is based on Newtonian fluid. In other words the temperature rise due to sliding is not considerd. This theory fails in the case of sliding. So to predict the accurate results, non-newtonian fluid must be considered with implementation of energy equation for the calculation of temperature. 'Kim' reduced the 3D heat transfer problem to 2D by assuming parabolic distribution of temperature across the film thickness, but this leads to inaccurate results.

The prediction of friction at point of contact is also important. The main cause of friction is the sliding of boundary layer on bearing. Also the surface topography plays important role in analyzing the friction. To predict the generated temperature several models are proposed. One of them is the 'one point model'. Firstly a researcher 'Jacod' reported master curves determined by interpolating the data using numerical techniques. After that, these master curves are used to determine the situation of parameters at point of contact, so geometry of contact becomes irrelevant. Also two dimensional model is proposed which considers oil conduction along the normal direction, by discretizing the geometry of contact and evaluating the heat at discrete points.

During its operation, some pressure waves are generated within the lubricant due to applied load. These waves decays with displacement from point of contact. It is predicted that this decay is exponential. So to properly review the EHL theory it is necessary to consider the effect of these pressure/discontinuties waves by expressing there parametrs in a function which is used to calculate the pressure.

The analysis of dimpled surface is also necessary to understand the EHL theory properly. It is investigated that, specimens with isotropic surfaces are better than superfinished specimens, when subjected to peeling test. Actually dimpled surfaces would induce pressure spikes, resulting in concentrated stresses. These stresses are the main cause of crack within the bearing. But in some cases, the lubricant fills the pits and try to enhance the revolution of journal within the bearing. This case is true for starved lubrication. Sometimes the pits are intentionally introduced to overcome the danger of starved lubrication.

Moreover in this paper, all the historical work done on the topic is discussed and their limitations as well. The limitations were present due to the fact that the factors like fatigue, pressure, EHL, Micro EHL were evaluated simultaneously particularly in a competitive to the failure. With the each new consideration a new model was developed like, Molecular dynamic model, CFD and Thin-film fluid model. However several phenomena are still undiscovered. Finally in this paper it is hoped that the engineers may find these three models working together to explore the failure of lubrication film in near future.