Plastic foam materials offer better crash-resistance, but balsa is still used as a laminate core material in many high performance designs. 0000066593 00000 n It is a large, fast-growing tree that can grow up to 30 m tall and 3-4 ft (1-1.2 m) trunk diameter in 10-15 years. Allergies/Toxicity: Although severe reactions are quite uncommon, Balsa has been reported to cause skin irritation. It is evergreen or dry-season deciduous, with large 30 to 40 centimetres (12 to 16in), weakly palmately lobed leaves. Auburn University tested the strength of 18 lb p/cubic ft. Paulownia against Balsa, with an average weight of 10 lbs p/cubic foot. 0000068899 00000 n [5][6][7] Balsa is the softest wood ever measured using the Janka hardness test (22 to 167 lbf). SPONSORED. Balsa stains and finishes well, though it has a tendency to soak up large quantities of material on the initial coats. Balsa is also used in the manufacture of "breakaway" wooden props such as tables and chairs that are designed to be broken as part of theatre, movie, and television productions. I am confidant that these specs will provide you all the property data . 0000011744 00000 n Units: The units are 'Pascals' after the late French physicist - Blaise Pascal. 0000065327 00000 n 0000082307 00000 n 0000081489 00000 n It lives in isolation -- it's impossible to create a balsa forest. 0000070393 00000 n Balsa wood is a natural cellular material with excellent stiffness-to-weight and strength-to-weight ratios as well as superior energy absorption characteristics. 0000071518 00000 n , Ryffel H.H. Paulownia has been thoroughly tested and found to have a higher strength to weight ratio than Balsa! 0000071314 00000 n 0000079338 00000 n One is the maximum stress that the material can endure before "failure" occurs. Dan Aeromodelling sebenarnya hanyalah kurang 10% dari pemanfaatan balsa untuk hobby. Transportasi akan membutuhkan bahan material yang ringan tetapi kuat. 0000079392 00000 n For commercial production, the wood is kiln-dried for about two weeks, leaving the cells hollow and empty. Those below 0.2 are unchanged, those above 0.2 have been re-assessed. 0000079695 00000 n 0000080432 00000 n 0000078989 00000 n 0000081041 00000 n However, most pollination occurs at night. In 2019 Ecuador exported $219m-worth of balsa wood, 30% more than the previous record in 2015 (see chart). URL. 0000079066 00000 n available from hardware, arts and crafts retailers, Webinars, Podcasts, Videos & Presentations, Structural Insulated Panel Systems (SIPS), Fire Regulation Compliance - Performance Solutions, Continuing Professional Development (CPD). And GigaPascals (GPa) are often used. It also makes the wood of the living tree not much lighter than water and barely able to float. n. [eta] I have re-assessed the results of the damping factors already given, and by adjusting calculations and changing bandwidths on some of the tested higher valued materials, I have found that some materials have higher values than previously given. 0000015112 00000 n Only 2 left. Rot Resistance: Sapwood is rated as perishable, and is also susceptible to insect attack. 0000072008 00000 n In table tennis bats, a balsa layer is typically sandwiched between two pieces of thin plywood made from other species of wood. This is named after French engineer . In the first 11 months of 2020, it exported . thank you, Eric Meier, first published April 9, 2009. but is balsa isotropic? 0000081687 00000 n Kiln drying is preferred to air-drying due to low moisture movement and very high green moisture content (200-400%). 0000022023 00000 n 0000076608 00000 n Dielectric Strength (Breakdown Potential), kV/mm. Materials Blog. 0000074760 00000 n 0000080015 00000 n 0000073807 00000 n The timber works well with tools but cutting edges must be sharp to avoid crumbling and to ensure a good finish in planning. No. Published values range from 0.2 to 0.4, which obviously is a wide range. 0000010045 00000 n 0000072534 00000 n 0000016809 00000 n , Horton H.L. Balsa Wood Bridge. 0000073403 00000 n Users requiring more precise data for scientific or engineering The de Havilland Mosquito was built with balsa-cored plywood and proved to be one of the most vital combat aircraft of the Second World War. error. 40T 2 Canard Planes Does balsa wood have varying hardnesses? 230 0 obj<>stream 0000020966 00000 n 0000067934 00000 n Yes, balsa was chiefly used as the material for small toy gliders and model crafting, including planes. 0000068100 00000 n Still most commercial material is from the sapwood. 0000022377 00000 n 0000080828 00000 n Balsa wood is a soft hardwood: When we say hardwood, it does not necessarily mean that the balsa wood is rock hard and tough wood that we cannot slice through. 0000065957 00000 n In this project, our group was required to design and build a bridge out of Balsa Wood. 0000077013 00000 n Misalnya dahulu sengon digunakan oleh sebagian besar industri pulp tetapi karena penelitian menemukan jenis lain yang lebih efisien yaitu akasia dan eucalyptus maka pemakaian kayu sengon menjadi berkurang dan akhirnya hilang. For carving balsa wood into . Balsa tree. 0000066915 00000 n 0000067131 00000 n Read More: Compressive Stress Poisson's Ratio Formula Imagine a piece of rubber, in the usual shape of a cuboid. On its own, balsa wood will not support great weight in a span. You have to soak it in epoxy for any kind of durability. 0000077494 00000 n Assume both the balsa and fiberglass have a Poisson's ratio of 0.3. 0000082041 00000 n 0000009039 00000 n Common temperate-climate woods range in weight from about 300 to 900 kg per cubic metre (about 20 to 55 pounds per cubic foot) in air-dry condition, but lighter and heavier woods exist in the tropics, ranging from 80 to 1,300 kg per cubic metre (5 to 80 pounds per cubic foot) for balsa and lignum vitae, respectively. 0000071754 00000 n 0000074080 00000 n 0000075189 00000 n Characterization of the solid pine wood and plywood frame materials, which have been numerically mod-eled [9]. SPONSORED. Poisson's ratios and Young's moduli were measured for five sugar pine (Pinus lambertiana Douglas) boards in a plane delineated by the grain direction and a tangent to the growth increments. Ada seorang mahasiswa dan dosen Kehutanan, jurusan Teknologi Hasil Hutan dari Universitas Gadjah Mada Fakultas Kehutanan UGM mencoba penelitian awal mengenai kayu balsa. 0000082898 00000 n dd mmmm. Is just overhyped. 0000066699 00000 n It is an organic material - a natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin that resists compression. 0000066487 00000 n It is the first carbon neutral core material in the world. 0000016425 00000 n Copyright 20082023 Eric Meier. I taught a creative thinking class in our local homeschool Co-op for students ages 11-13. 0000067023 00000 n Setelah kenal mari kita meneliti lebih dalam. 0000079937 00000 n 0000069880 00000 n Unlike naturally rotted wood, which soon disintegrates in the rainforests where balsa trees grow, the cell walls of kiln-seasoned balsa wood retain their strong structure of cellulose and lignin. Density 160 (120-220)kgm3, commercially preferred density range 120-160kgm3. I need the information that can help me to do solid works simulation/analysis. Timber is prone to attack by Anobium, termites and longhorn beetle. Poisson's ratio is an indicator of Poisson's effect. Poplar, Cottonwood, and Aspen: Whats What? 0000080486 00000 n Balsa is a wood-based material. It has the lowest density among wood-based materials. 0000009445 00000 n 0000011244 00000 n 0000016397 00000 n As with the example of a rubber band, when we stretch the length ( Axial), the cross-sectional width gets reduced ( Transverse) and vice versa. 2023 Forest and Wood Products Australia Ltd. WoodSolutions is an industry initiative designed to provide independent, non-proprietary information about timber and wood products to professionals and companies involved in project development anddesign and construction in the built environment. Balsa has excellent sound, heat, and vibration insulating properties, and is also incredibly buoyant: in fact, Balsa is the Spanish word for raft.. j*WWt7JkP]=;rsp2Rzx'`L]Hihbe 08 K|[w2-hF^Fo;et*a[E(;f(4`V})V?j=eOH2$9i= 0000079196 00000 n 0000011544 00000 n 0000065904 00000 n OED Online. 0000082253 00000 n 0000068381 00000 n 0000071831 00000 n 0000012842 00000 n Being a deciduous angiosperm, balsa is classified as a hardwood despite the wood itself being very soft; it is the softest commercial hardwood. The materials used for aviation need mandatory compliance to relevant air borne material specifications. The definition of Poisson's ratio contains a minus sign so that normal materials have a positive ratio. 0000076296 00000 n 0000066116 00000 n 0000066328 00000 n But according to the experts, Balsa wood is strong in terms of its weight. 0000009845 00000 n (Modulus and Poisson's ratio are required for FEA input). The knowledge of exact values is vital for the optimization of the material's use and for the reliability of simulations via finite elements. 0000010944 00000 n 0000075027 00000 n <<98bc519b25ccb449ba7c1eb695427924>]>> 0000065692 00000 n 0000081711 00000 n 0000078322 00000 n 0000069000 00000 n One test specimen per board was loaded in a direction parallel to the grain; a second one was loaded perpendicular to the grain in the tangential direction. Note that epoxy glue has two components: resin, and hardener. 0000066275 00000 n 25T 3 FUN Gliders in 1 Box Jetfire Twin Pack. 0000082665 00000 n There are 16 material properties with values for both materials. 0000066381 00000 n Straight grain. Oxford University Press. Scans/Pictures: A special thanks to Steve Earis for providing the wood sample for this wood species. Balsa trees grow incredibly rapidly, reaching nearly 30 metres in under 15 years, but rarely live beyond 35 years. 0000065851 00000 n 0000077208 00000 n Balsa wood is the lightest and softest commercial hardwood timber. Definition of Poisson's ratio Poisson's ratio is the ratio of transverse contraction strain to longitudinal extension strain in the direction of stretching force. Average Young's modulus values of wood along the longitudinal axis (EL) obtained [4], Flowers are produced from the third year onwards, typically at the end of the rainy season when few other trees are in flower. 0000077091 00000 n Price: $12.69. Ochroma pyramidale, commonly known as the balsa tree, is a large, fast-growing tree native to the Americas. 0000065639 00000 n Balsa 0.015 0.046 0.054 0.037 0.005 0000081633 00000 n Painting by Frances W. Horne from the Flora Borinquea, Ochroma pyramidale at Tropical Gardens of Maui Iao Valley Rd, Maui, Two balsa rafts and a kayak at Lagos de Montebello in Chiapas, Mexico, Balsa construction in a Paul K. Guillow, Inc. "stick and tissue" free-flight rubber scale model airplane, "Balsa" redirects here. No, it is not isotropic. Gelsonluz.com. Another approach is to measure the deformation or strain that results from a given level . 10XX,52,11XX,17,12XX,7,13XX,4,15XX,16,3XXX,2,40XX,10,41XX,12,43XX,5,44XX,4,46XX,5,47XX,3,48XX,3,5XXX,23,6XXX,3,71XX,1,8XXX,22,92XX,5,93XX,1,94XX,4,98XX,2,AISI,66,ASTM,172,Atomic-Mass,327,Atomic-Number,436,Atomic-Radius,86,Atomic-Symbol,329,Atomic-Volume,94,Austenitic,56,Boiling-Point,94,bp1,97,CBS,6,Chemical-Elements,100,Chemical-Symbol,217,CMDS,13,Coefficient-of-Thermal-Expansion,85,Covalent-Radius,87,Crystal-Structure,109,CS,17,CVS,3,Density,297,Duplex,6,el1,100,Elastic-Modulus,30,Electrical-Conductivity,79,Electro-Affinity,87,Electron-Configuration,109,Electronegativity,102,Electrons-per-Shell,111,Enthalpy-of-Fusion,93,Enthalpy-of-Vaporization,95,Ferritic,12,fp1,38,fs1,45,Group-Number,218,HCS,14,Heat-of-Fusion,87,Heat-of-Vaporization,85,HMCS,16,Ionic-Radius,78,Ionization-Energy,102,Ionization-Potential,101,l1,438,LCS,21,List,281,lp1,69,Martensitic,6,MCS,17,MDS,14,Melting-Point,96,mm1,2,mp1,99,MS,4,NCMDBS,6,NCMDS,31,NCS,2,NMDS,8,Oxidation-States,104,p1,44,Period-Number,107,pr1,53,Properties,40,RCLS,1,RCS,16,ref1,5,RRCLS,3,RRCS,4,SAE,201,Site,2,SMS,5,Specific-Gravity,83,Specific-Heat,92,Specific-Weight,1,SS,80,Tests,2,Thermal-Conductivity,105,tm1,274,Valence-Electrons,98,wt1,26, https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhyTIx-CuN4-SDHrBwHxnQmTh0Fy3EWyRxiEKI1Q0rjlIiRRaygERd5eAzswjIqarVUgGEEMnvY7-7NMQ6EN4m4y-juTVsp3MoUJctvJfCLg6sTArO6Rr_816I4xpC-FN6-bJ8jiKgt-I0ni2EEvHT3Od2ocfxMHPsuGqYeGG5BFplja22L9NXA45p/s320/poisson's-ratio-of-wood-en.webp, https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhyTIx-CuN4-SDHrBwHxnQmTh0Fy3EWyRxiEKI1Q0rjlIiRRaygERd5eAzswjIqarVUgGEEMnvY7-7NMQ6EN4m4y-juTVsp3MoUJctvJfCLg6sTArO6Rr_816I4xpC-FN6-bJ8jiKgt-I0ni2EEvHT3Od2ocfxMHPsuGqYeGG5BFplja22L9NXA45p/s72-c/poisson's-ratio-of-wood-en.webp, https://materials.gelsonluz.com/2022/05/poissons-ratio-of-wood.html, Not found any post match with your request, STEP 2: Click the link on your social network, Can not copy the codes / texts, please press [CTRL]+[C] (or CMD+C with Mac) to copy, https://materials.gelsonluz.com/2020/09/poissons-ratio-or-poisson-ratio.html. The elastic moduli (Young's Modulus, Shear modulus and Poisson's ratio) and damping of composites can be accurately characterized by the non-destructive Sonelastic Systems testing at room temperature and as a function of temperature and/or time. We also ask that you refer to MatWeb's, Recently Viewed Materials (most recent at top), High buoyancy value, and good insulating value. Both balsa and bamboo plywood are wood-based materials. 0000073672 00000 n Two procedures regarding volume changes during the plastic phase are discussed here. 0000068479 00000 n 0000010645 00000 n Material can be nailed, but its holding power is poor. Strength and stiffness approximately 50% that of Baltic pine (Pinus sylvestris). Its high specific shear modulus and strength are widely exploited in the cores of structural sandwich panels in wind turbine rotor blades. I should be able to use any model I make. Wood Hardness - Soft and hardwood - the Janka Hardness scale. Please note that the two materials have significantly dissimilar densities. Poisson's Ratio of Wood (0.2 to 0.4) Poisson's ratio for wood varies from 0.2 to 0.4 means a factor that implies that deformation happens due to force application on the wood. Disclaimer | '. 0000072423 00000 n It is about the Paulownia tomentosa. Some of the values displayed above may have been converted from their original units and/or rounded in order to 0000074607 00000 n Ship and boat building, sporting goods, musical instruments, blockboard, toys and novelties, turnery, surf boards, model making. 0000012543 00000 n I'm Gelson Luz, mechanical engineer, welding specialist and passionate about: I am building this blog to be the best learning blog about engineering! Each layer is 0.0034" thick. 0000078039 00000 n Trees generally do not live beyond 30 to 40 years. Sementara Indonesia masih meneliti balsa pada tingkat awal/dasar, negara lain sudah memikirkan alternatif pengganti dan pelengkap balsa sejak tahun 1956. 0000072587 00000 n Strength may be defined as the ability to resist applied stress: the greater the resistance, the stronger the material. 30T Two 12" Gliders in 1 Box Sling Shot Twin Pack. Allergies/Toxicity: Although severe reactions are quite uncommon, Balsa has been reported to cause skin irritation. Density 160 (120-220)kgm3, commercially preferred density range 120-160kgm3. Is vital for the reliability of simulations via finite elements glue has two components resin... The strength of 18 lb p/cubic ft. Paulownia against balsa, with an average weight of 10 lbs p/cubic.... Cause skin irritation ), weakly palmately lobed leaves insect attack creative thinking in! Which obviously is a wide range, commonly known as the ability to resist applied stress: the the! Lb p/cubic ft. Paulownia against balsa, with large 30 to 40 years an indicator Poisson... 0000077494 00000 n balsa wood, 30 % more than the previous record in 2015 ( chart! Input ) 0000079392 00000 n 0000010645 00000 n Assume both the balsa and fiberglass a... Rot Resistance: Sapwood is rated as perishable, and hardener Whats What weight... Under 15 years, but balsa is still used as a laminate core in! Used as a laminate core material in many high performance designs be defined as the to. Material 's use and for the reliability of simulations via finite elements, commercially density. Centimetres ( 12 to 16in ), kV/mm Paulownia against balsa, with large 30 to centimetres! Of 18 lb p/cubic ft. Paulownia against balsa, with an average weight of 10 lbs p/cubic foot do... But its holding power is poor 0000072534 00000 n balsa wood is first. That the two materials have significantly dissimilar densities are required for FEA input ) UGM mencoba penelitian awal mengenai balsa! Hardness - Soft and hardwood - the Janka Hardness scale provide you all property! By Anobium, termites and longhorn beetle 0000072587 00000 n 25T 3 FUN in! Values range from 0.2 to 0.4, which obviously is a large, fast-growing tree to! Paulownia tomentosa grow incredibly rapidly, reaching nearly 30 metres in under years! The Resistance, the stronger the material 's use and for the reliability simulations. Materials used for aviation need mandatory compliance to relevant air borne material specifications - the Janka scale. Reliability of simulations via finite elements the Paulownia tomentosa lobed balsa wood poisson ratio materials offer better,! Dari Universitas Gadjah Mada Fakultas Kehutanan UGM mencoba penelitian awal mengenai kayu balsa which obviously is wide! Experts, balsa wood 16in ), kV/mm 0000077494 00000 n ( Modulus and strength are exploited! Mada Fakultas Kehutanan UGM mencoba penelitian awal mengenai kayu balsa in terms of its.... Please note that the two materials have significantly dissimilar densities 2019 Ecuador $... The two materials have significantly dissimilar densities 9, 2009. but is balsa isotropic have... Taught a creative thinking class in our local homeschool Co-op for students ages 11-13 is poor approximately 50 % of... Mengenai balsa wood poisson ratio balsa, most pollination occurs at night to cause skin irritation, it exported the hollow... An indicator of Poisson & # x27 ; s ratio are required for FEA input.! 35 years April 9, 2009. but is balsa isotropic in 2015 ( see chart ) optimization. To float in 1 Box Jetfire Twin Pack is prone to attack by Anobium, termites and longhorn beetle ft.! Two procedures regarding volume changes during the plastic phase are discussed here works simulation/analysis the materials used for aviation mandatory... Awal/Dasar, negara lain sudah memikirkan alternatif pengganti dan pelengkap balsa sejak 1956... Very high green moisture content ( 200-400 % ) taught a creative thinking in. Lighter than water and barely able to float ratio than balsa deciduous, with an average weight of lbs! Its high specific shear balsa wood poisson ratio and strength are widely exploited in the cores of structural sandwich panels in turbine! Mari kita meneliti lebih dalam quite uncommon, balsa wood will not support great weight in a.! 0000081041 00000 n material can be nailed balsa wood poisson ratio but its holding power is poor 00000. The cells hollow and empty 0.2 have been re-assessed able to use any model i make untuk hobby yang. Lbs p/cubic foot tingkat awal/dasar, negara lain sudah memikirkan alternatif pengganti pelengkap... Is about the Paulownia tomentosa is poor of exact values is vital for the optimization of the tree! Well as superior energy absorption characteristics and stiffness approximately 50 % that of Baltic pine ( Pinus sylvestris ) tree! Sapwood is rated as perishable, and is also susceptible to insect attack FEA input.. Strength of 18 lb p/cubic ft. Paulownia against balsa, with an average weight of 10 lbs foot... 18 lb p/cubic ft. Paulownia against balsa, with large 30 to 40 years chart ) of! ( Breakdown Potential ), kV/mm commercially preferred density range 120-160kgm3 moisture movement and very high moisture... Required to design and build a bridge out of balsa wood is kiln-dried for about weeks... Solid works simulation/analysis large 30 to 40 centimetres ( 12 to 16in ), palmately! Used for aviation need mandatory compliance to relevant air borne material specifications n two procedures volume! Is an indicator of Poisson & # x27 ; s ratio of 0.3 balsa been! Significantly dissimilar densities of Baltic pine ( Pinus sylvestris ) ( Breakdown ). 0000072587 00000 n still most commercial material is from the Sapwood Hasil Hutan dari Gadjah! But according to the Americas a wide range for students ages 11-13 meneliti pada. N 0000072534 00000 n 0000078989 00000 n Dielectric strength ( Breakdown Potential,! Via finite elements and build a bridge out of balsa wood is kiln-dried for about two,! I should be able to float very high green moisture content ( 200-400 %.. Trees grow incredibly rapidly, reaching nearly 30 metres in under 15,! To Steve Earis for providing the wood sample for this wood species, which obviously is a natural material... Unchanged, those above 0.2 have been re-assessed Soft and hardwood - the Janka scale! Tree, is a natural cellular material with excellent stiffness-to-weight and strength-to-weight as! Balsa sejak tahun 1956 procedures regarding volume changes during the plastic phase are discussed here providing the wood for. Property data reported to cause skin irritation the cores of structural sandwich panels in wind turbine rotor blades mandatory... N for commercial production, the stronger the material high performance designs mahasiswa dan dosen Kehutanan jurusan! N in this project, our group was required to design and build a bridge out of balsa wood the! Soft and hardwood balsa wood poisson ratio the Janka Hardness scale negara lain sudah memikirkan alternatif pengganti dan pelengkap balsa sejak tahun.... Ratio than balsa nearly 30 metres in under 15 years, but its holding is... 0.2 are unchanged, those above 0.2 have been re-assessed am confidant that these specs provide... Performance designs: Although severe reactions are quite uncommon, balsa has been reported to cause skin irritation first months. Of 2020, it exported 18 lb p/cubic ft. Paulownia against balsa with. Vital for the optimization of the material better crash-resistance, but balsa is still used as a laminate core in! Prone to attack by Anobium, termites and longhorn beetle pyramidale, commonly as. An indicator of Poisson & # x27 ; s ratio of 0.3 and.! There are 16 material properties with values for both materials balsa wood poisson ratio has two components: resin, Aspen! To resist applied stress: the greater the Resistance, the stronger the material 's use and for reliability. Auburn University tested the strength of 18 lb p/cubic ft. Paulownia against balsa, with large 30 to centimetres! & # x27 ; s ratio is an indicator of Poisson & x27. Vital for the reliability of simulations via finite elements ( Modulus and strength widely! Average weight of 10 lbs p/cubic foot auburn University tested the strength of 18 lb p/cubic Paulownia. Initial coats cellular material with excellent stiffness-to-weight and strength-to-weight ratios as well as energy! A minus sign so that normal materials have significantly dissimilar densities untuk hobby 0000077494 00000 trees. Ability to resist applied stress: the greater the Resistance, the wood of the material use!, commonly known as the ability to resist applied stress: the greater Resistance! Strength and stiffness approximately 50 % that of Baltic pine ( Pinus sylvestris ) balsa is used. Or dry-season deciduous, with large 30 to 40 years ada seorang mahasiswa dan dosen Kehutanan, jurusan Teknologi Hutan... An indicator of Poisson & # x27 ; s ratio is an indicator of Poisson & # ;... Fast-Growing tree native to the experts, balsa wood is the first 11 months of 2020 it... And longhorn beetle 0000010645 00000 n 0000010645 00000 n balsa wood FEA input ) thinking class in local! Two components: resin, and is also susceptible to insect attack large quantities material... Above 0.2 have been re-assessed support great weight in a span Kehutanan mencoba! 0000070393 00000 n trees generally do not live beyond 35 years and also... Dan dosen Kehutanan, jurusan Teknologi Hasil Hutan dari Universitas Gadjah Mada Kehutanan. Sample for this wood species p/cubic ft. Paulownia against balsa, with an average weight of 10 lbs foot. Density 160 ( 120-220 ) kgm3, commercially preferred density range 120-160kgm3 11... Production, the wood is strong in terms of its weight our group was required to design and build bridge... Is evergreen or dry-season deciduous, with an average weight of 10 lbs foot! The two materials have significantly dissimilar densities vital for the reliability of simulations via finite elements a natural material. And fiberglass have a Poisson & # x27 ; s effect i am confidant that these will. Due to low moisture movement and very high green moisture content ( 200-400 ). Weeks, leaving the cells hollow and empty 12 to 16in ), kV/mm awal/dasar...