Transient thermal analysis

http://www.simutechgroup.com/FEA/fea-tips-tricks-thermal-transient.html

How to create an animation video in ANSYS Workbench

Please proceed to the following link

http://www.simutechgroup.com/FEA/fea-tips-tricks-creating-ansys-videos.html

How to build a user-defined chart from ANSYS Workbench

Biodegradable plastic in automotive

Recently, plastic composites consumption in automotive industry has experienced a spectacular growth with many applications in interior, exterior and under-hood components.  Pressure in fuel-efficient and low-polluting vehicles increases use of engineering plastics to make lighter weight products (Bellmann 1999; Allred 2000)[ Marsh, 2003, Mann D., 1999]. Amount of plastic used in current average automobile increased triple compared to those in 1975, with 14% to total weight, approximately 145.2 kg per vehicle in 2005 (Fig. 1.1b). Consequently, plastic waste from end-of-life of vehicles (ELV) becomes increase faster. In Canada and United States, there are about 11 million of vehicles with 1.6 million tones of ELV plastic part were dump into a landfill each year [Duval, 2007; Mohanty]. While in UK, around 2 million of vehicles reach the end of their life each year (Bismarck 2006).

Percentage of plastic components in each vehicle part to Total Plastic used

Percentage of Material Relative to Total Weight [Source: http://www.research.bayer.com]

The environmental awareness of the society has risen to the point that plastic waste should be reduced protection of natural resources and reduction CO₂ emission. Plastics make up significant proportion of the volume of domestic and industrial waste (10 - 30%), which degrade very slowly and equally resistant to natural process [Arostegui et al, 2008; Kolybaba, 2003]. They contain chemical substances that could present a hazard for the environment and also need more energy to produce [Marsh, 2003; Rosa, 2001]. Accumulation of plastic residue makes difficulty of water and oxygen to circulate and delays living of organic matters that cause damage to the environment and all living creatures.

Conventional method used as plastic waste reduction was disposal in land fill sites. Nowadays, the focus is on the reuse and recycle of waste materials because of ecological concern and limited space of land filling [Yoshioka et al, 2008]. By 2015, European Commission (EC) through European Guideline 2005/53/EG obligates that vehicles should be constructed of 95% recyclable materials with 85% recoverable through reuse or mechanical recycling  (Ashori 2008).   Even that reuse of plastic product could be the most environment-friendly method; there should be further checking to make sure that the material meets the required quality. Several problems also faced in recycling, such as difficulty to recycle due to complex polymer structure, loss of some advantageous properties and requirement of sophisticated technology or greater energy (Bellmann 1999; Allred 2000; Ashori 2008); Yoshioka et al, 2008; Selke, 2002]. Surveys in Germany have shown that basically only around 40% of the plastics used in a vehicle are fit for mechanical recycling (Bellmann 1999). Recycling conventional plastic composites releases dust and hazardous gasses (CO2, NO_x and SO_x) into the atmosphere.

To overcome those problems, the automotive industry should seek more environmental friendly material to minimize the creation of plastic waste. An innovative solution to the disposal of ELV plastic parts can be the use of biodegradable plastic. They are environmental friendly, eliminate hazardous substances into the soil and in the other hand provide appropriate mechanical and physical properties (Bismarck 2006; Ashori 2008)[Environment Australia, 2002; Malinconico, 2008].  Some of them are made from renewable resources therefore reduce the emission of hydrocarbon. 

Di ujung tanduk

Gleks..... sudah tahun ke-3 ternyata...Supervisor aka bang Igor sudah mulai menyiapkan jadwal aku harus kirim draft Bab I dan Bab II Januari nanti.

Sudah ngapain aja nih 3 tahun ini? Rasanya minder berat seorang teman di Laser group udah submit 5 paper journal. Waaa..... sementara aku baru mampu menyelesaikan 2 conference paper, 1 published paper journal dan 1 calon paper journal. Mau submit ke Springer masih belum nemu caranya pakai template-nya

Kliping: Safety factor for dummy

Old joke:  “You see the glass as half empty, I see the glass as half full, but an engineer sees the same glass and says ‘it is overdesigned for the amount of fluid it holds.’”

     When an engineer starts out to build something, one of the first questions to be answered is how much load must it carry in normal service?  The next question is similar:  hom much load must it carry at maximum?  An engineer can study those questions deeply or very superficially, but having a credible answer is a vital step in at the start of a design process. 

     Here is an example.  If you design and build a step ladder which just barely holds your weight without breaking, what will happens after the holidays when your weight may be somewhat more than it was before you eat Aunt Martha's Christmas dinner?  You really don’t want to throw out your stepladder in January and build a new one do you?  Obviously you would should build a stepladder that can hold just a little bit more.  Don't forget what might happen if you loan your stepladder to your coach-potato neighbor who weighs a lot more than you do?  Can you saylawsuit?

     So how do you determine what your stepladder should hold?  Do you find out who is the heaviest person in the world and make sure it will hold that person?  Probably not.  Better, pick a reasonable number that covers, say, 95% of all folks, design the ladder to that limit and put a safety sticker on the side listing the weight limit.  Yep, that is how most things are constructed.

     But that is not all.  Once you determine normal or even the maximum load it is a wise and good practice to include a “factor of safety”.  That means that you build your stepladder stronger than it needs to be.  This helps with the idiots that don’t read the safety sticker; it also helps protect for some wear and tear, and it also can protect if the actual construction of your stepladder falls somewhat short of what you intended.  So you might build your stepladder with a FS of 2.  That would cover 95% of all folks with plenty of margin for foolish people that try to accompany their friend climbing the ladder; or when your ladder has been in service for 25 years (like mine), or when your carpenter buddy builds the stepladder with 1/4” screws rather than ½” screws like you told him to.

     Factors of safety are not pre-ordained.  They have been developed over the years through experience and unfortunately through failures.  Some factors of safety are codified in law, some are determined by professional societies and their publications, and some are simply by guess and by golly.  Engineering is not always as precise as laypeople think.

     

     It’s a dry passage but I’d like to quote from one of my old college textbooks on this subject (Fundamentals of Mechanical Design, 3^rd Edition, Dr. Richard M. Phelan, McGraw-Hill, NY, 1970, pp 145-7):

“ . . . the choice of an appropriate factor of safety is one of the most important decisions the designer must make. Since the penalty for choosing too small a factor of safety is obvious, the tendency is to make sure that the design is safe by using an arbitrarily large value and overdesigning the part.  (Using an extra-large factor of safety to avoid more exacting calculations or developmental testing might well be considered a case of “underdesigning” rather than “overdesigning.”)   In many instances, where only one or very few parts are to be made, overdesigning may well prove to be the most economical as well as the safest solution.  For large-scale production, however, the increased material and manufacturing costs associated with overdesigned parts result in a favorable competitive position for the manufacturer who can design and build machines that are sufficiently strong but not too strong.

            As will be evident, the cost involved in the design, research, and development necessary to give the lightest possible machine will be too great in most situations to justify the selection of a low factor of safety.  An exception is in the aerospace industry, where the necessity for the lightest possible construction justifies the extra expense.”

            "Some general considerations in choosing a factor of safety are  . . . the extent to which human life and property may be endangered by the failure of the machine . . . the reliability required of the machine . . . the price class of the machine.”

            Standards for factors of safety are all over the place.  Most famously, the standard factor of safety for the cables in elevators is 11.  So you could, if space allowed, pack eleven times as many people into an elevator as the placard says and possibly survive the ride.  For many applications, 4 is considered to be a good number.  In the shuttle program the standard factor of safety for all the ground equipment and tools is 4.  

            When I was the Program Manager for the Space Shuttle, there were a number of times when a new engineering study would show that some tool either could be exposed to a higher maximum load than was previously thought, or that the original calculations were off by a small factor, or for some reason the tool could not meet the FS of 4.  In those circumstances, the program manager – with the concurrence of the safety officers – could allow the use of the tool temporarily – with special restrictions – until a new tool could be designed and built. These “waivers” were always considered to be temporary and associated with special safety precautions so that work could go forward until the standard could once again be met with a new tool.

            In the aircraft industry, a factor of safety standard is 1.5.  Think about that when you get on a commercial airliner some time.  The slim factor of safety represents the importance of weight in aviation.  It also means that much more time, engineering analysis, and testing has gone into the determination of maximum load and the properties of the parts on the plane.

            For some reason, lost in time, the standard FS for human space flight is 1.4, just slightly less than that for aviation.  That extra 0.1 on the FS costs a huge amount of engineering work, but pays dividends in weight savings.  This FS is codified in the NASA Human Ratings Requirements for Space Systems, NPR 8705.2.  Well, actually, that requirements document only references the detailed engineering design requirements where the 1.4 FS lives. 

            Expendable launch vehicles are generally built to even lower factors of safety:  1.25 being commonplace and 1.1 also used at times.  These lower factors of safety are a recognition of the additional risk that is allowed for cargo but not humans and the extreme importance of light weight.

            It is common for people to talk about human rating  expendable launch vehicles with a poor understanding of what that means.  Among other things, it means that the structure carrying the vast loads which rockets endure would have to be significantly redesigned to be stronger than it currently is.  In many cases, this is tantamount to starting over in the design of the vehicle.

            So to the hoary old punch line:  Would you want to put your life on the top of two million parts, each designed and manufactured by the lowest bidder?

Source: http://blogs.nasa.gov/cm/blog/waynehalesblog/posts/post_1229459081779.html

Langkah kaki menuju surga (insya allah)

Langkah-langkah kaki kami berderap menyusuri De carle st menuju moreland rd. Celoteh riang, canda ringan dan senyum mengembang mengiringi ayunan kaki kami. Panas terik matahari tak membuat kami mengeluh. Derai hujan tak membuat kami surut melangkah.

Kami tinggalkan sejenak kenikmatan bermain di playground. Kami tinggalkan serunya main catur bersama Simon. Kami tinggalkan asyiknya menyanyi bareng di Performing Art room.

Kami langkahkan kaki menuju tempat kami diijinkan bersujud kepada-Mu. Menuju barisan yang lurus mengikuti sunnah Rasul-Mu. Menuju majelis mulia melantunkan doa pada-Mu. 

Mungkin saat ini kaki kecil kami belum mampu melangkah panjang. Tapi Insya Allah saat dewasa nanti, kaki ini yang membawa kami menjelajah dunia. Insya Allah kaki ini yang membantu kami mencari tempat-tempat sujud yang akan bersaksi di yaumul hisab. Dan Insya Allah kaki ini pula yang akan meringankan langkah kami menuju jalan ke surga-Mu, ya Allah

Hawthorn, mengenang 2 term sholat duhur bersama anak-anak sholeh di Moreland Primary School