Safety Factor Mari berbicara tentang safety factor. Apa itu safety factor, mengapa harus ada safety factor dan bagaimana menghitung safety factor.
Apa itu Safety Factor?
Jika menyadur dari wikipedia: Factor of safety (FoS), also known as (and used interchangeably with) with) safety factor (SF), is a term describing the structural capacity of a system beyond the expected loads or actual loads .
Jadi dapat kita artikan kapasitas sistem diluar dari beban yang dipediksikan. Jadi dapat dikatakan untuk menjadi pengaman apabila sistem mengalami beban diluar perhitungan.
Mengapa harus ada safety factor?
Seperti yang telah disebutkan diatas bahwa safety factor adalah sebagai pengaman pada sistem jika pada suatu keadaan sistem tersebut menerima beban diluar dari perhitungan. Tujuannya agar design kita tidak failed (gagal) pada keadaan tersebut. Mengapa sistem yang sudah diperhitungan bisa mendapat beban (load) berlebih diluar perhitungan? Ada beberapa faktor yang mempengaruhi, biasanya dibagi atas faktor internal dan eksternal.
Faktor Internal:
Ketidak murnian dari material. Sulit untuk menjamin bahwa setiap material memiliki kekuatan yang serupa meskipun jenisnya sama. Akibat dari ketidakmurnian tersebut bedampak pada kekuatan pada material yang akhirnya berdampak pada kekuatan design Proses Manufakturing yang kurang sempurna. P roses manufakturing yang kurang sempurna mungkin dapat mengakibatkan mengakibatka n defect (cacat) geometri pada design yang akhirnya mengakibatkan turunnya kekuatan design
Faktor Eksternal
Lingkungan dan cuaca dapat mempengaruhi design dengan signifikan. contoh sebuah design yang dioperasikan di pantai, faktor udara pantai yang mengandung garam dapat mengakibatkan karat pada design, sehingga dapat terjadi penurunan kekuatan. Kecelakaan. Kita tidak menginginkan kecelakaan, tetapi kecelakaan terkadang terjadi. Agar design kita tidak failed ketika mengalami situasi yang tidak diperhitungkan tersebut maka harus ada safety factor. Contoh Pelat pada pintu mobil yang yang dibuat lebih tebal tebal untuk menghindari menghindari benturan keras dari samping.
Bagaimana menghitung Safety Factor?
Dalam penentuan safety factor, ada beberapa aspek yang wajib untuk kita perhatikan. P ertama, jika kita bekerja dengan menggunakan standard tertentu, maka kita harus mengikuti besarnya safety factor yang sudah ditentukan oleh standard. Kedua, jika kita mendesign sesuatu yang belum ada standardnya, maka besarnya safety faktor ditentukan sendiri oleh design dengan melihat faktor-faktor yang telah disebutkan diatas.
Rumus Safety Factor:
Secara rumus, safety factor adalah perbandingan antara besarnya beban batas kekuatan material dengan beban yang terjadi pada design.
Agar keamanan dapat tercapai, maka design load atau beban yang terjadi tidak boleh lebih besar daripada batas beban dari material. Artinya, nilai dari safety factor ini harus lebih besar daripada 1 (satu). Berapa besarnya? kembali yang sudah dijelaskan diatas. Tetapi satu catatan penting adalah semakin besar safety factor, akan berdampak pada banyaknya pemakaian material. Yang akhirnya akan berdampak pada cost (biaya). sebagai designer, kita juga harus mempertimbangkan faktor biaya selai faktor teknis lainnya.
- See more at: http://communities.autodesk.com/indonesia/forum/topic/manufacturing/inventor/safetyfactor#sthash.qRTKzPPb.dpuf
Factor of safety From Wikipedia, the free encyclopedia
See also: Safety factor (plasma physics) Factor of safety (FoS), also known as (and used interchangeably with) safety factor (SF), is a term describing the structural capacity of a system beyond the expected loads or actual loads. Essentially, how much stronger the system is than it usually needs to be for an intended load. Safety factors are often calculated using detailed analysis because comprehensive testing is impractical on many projects, such as bridges and buildings, but the structure's ability to carry load must be determined to a reasonable accuracy. Many systems are purposefully built much stronger than needed for normal usage to allow for emergency situations, unexpected loads, misuse, or degradation.
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Definition[edit] There are two distinct definitions for the factor of safety: One as a ratio of absolute strength (structural capacity) to actual applied load, this is a measure of the reliability of a particular design. The other use of FoS is a constant value imposed by law, standard, specification, contract or custom to which a structure must conform or exceed. The first use (a calculated value) is generally referred to as a factor of safety or, to be explicit, a realized factor of safety . The second use (a required value) as a design factor , design factor of
safety or required factor of safety . However, between various industries and engineering groups usage is inconsistent and confusing, it is important to be aware of which definition(s) are being used. The cause of much confusion is that various reference books and standards agencies use the factor of safety definitions and terms differently. Design codes and structural andmechanical engineering textbooks often use "Factor of Safety" to mean the fraction of total structural capability [1][2][3]
over that needed
(first use). Many undergraduate Strength of Materials books use "Factor of
Safety" as a constant value intended as a minimum target for design[4][5][6] (second use).
Calculation[edit] There are several ways to compare the factor of safety for structures. All the different calculations fundamentally measure the same thing: how much extra load beyond what is intended a structure will actually take (or be required to withstand). The difference between the methods is the way in
which the values are calculated and compared. Safety factor values can be thought of as a standardized way for comparing strength and reliability between systems. The use of a factor of safety does not imply that an item, structure, or design is "safe". Many quality assurance,engineering design, manufacturing, installation, and end-use factors may influence whether or not something is safe in any particular situation.
Design factor and safety factor [edit] The difference between the safety factor and design factor (design safety factor) is as follows: The safety factor is how much the designed part actually will be able to withstand (first "use" from above). The design factor is what the item is required to be able to withstand (second "use"). The design factor is defined for an application (generally provided in advance and often set by regulatory code or policy) and is not an actual calculation, the safety factor is a ratio of maximum strength to intended load for the actual item that was designed.
Design load being the maximum load the part should ever see in service.
By this definition, a structure with a FOS of exactly 1 will support only the design load and no more. Any additional load will cause the structure to fail. A structure with a FOS of 2 will fail at twice the design load.
