Materials | Wobbl

Terminal

$ wobbl run part.step -m 6061-t6 ...$ wobbl materials

Names are forgiving, so aluminum, 6061, stainless, polycarbonate and pla+ all find the right entry, and a typo gets a suggestion. Each material carries its source in the assumptions of every result.

The built in materials

Key	Material	Made	Limit (MPa)	Judged by	Default target
`pla`	PLA, 3D printed	printed	50	tensile strength	2.5
`petg`	PETG, 3D printed	printed	47	yield	2.5
`abs`	ABS, 3D printed	printed	33	yield	2.5
`asa`	ASA, 3D printed	printed	35	yield	2.5
`nylon`	Nylon PA6, conditioned	printed	50	yield	2.5
`pa12`	Nylon PA12, SLS or MJF	printed	48	yield	2
`pc`	Polycarbonate	molded	62	yield	2
`hdpe`	HDPE	molded	26	yield	2.5
`6061-t6`	Aluminum 6061-T6	wrought	276	yield	1.5
`7075-t6`	Aluminum 7075-T6	wrought	503	yield	1.5
`6063-t5`	Aluminum 6063-T5	wrought	145	yield	1.5
`5052-h32`	Aluminum 5052-H32	wrought	193	yield	1.5
`a356-t6`	Aluminum A356-T6, sand cast	cast	165	yield	2
`mild-steel`	Mild steel, ASTM A36	wrought	250	yield	1.5
`4140`	Steel 4140, quenched and tempered	wrought	655	yield	1.5
`ss304`	Stainless steel 304, annealed	wrought	215	yield	1.5
`ti-6al-4v`	Titanium Ti-6Al-4V	wrought	880	yield	1.5
`copper`	Copper C110	wrought	69	yield	1.5
`brass`	Brass C360	wrought	310	yield	1.5
`wood`	Douglas fir, along the grain	natural	50	tensile strength	3
`plywood`	Birch plywood	natural	35	tensile strength	3
`fr4`	FR4 PCB laminate, in plane	laminated	300	tensile strength	2
`li-ion-cell`	Li-ion cell, lumped		10	tensile strength	1.5

Materials judged by yield use von Mises stress, and the ones judged by tensile strength use the largest principal stress, which is how brittle materials crack. wobbl materials also lists stiffness, density, thermal conductivity and the service temperature that heat studies use as their default limit.

Your own values

Give any properties after custom:, in MPa and kg/m3.

Flag

-m "custom:E=72400,nu=0.33,yield=165,process=cast"

The keys are E, nu, yield (or sy), uts, density (or rho), k for conductivity, cp for specific heat, cte and tmax for the service temperature, plus process and ductile. The process says how the part is made, one of printed, molded, cast, wrought, natural or laminated, and it sets the caveats the result lists along with the layer strength for prints. Anything you leave out comes from the library material made the same way that is closest in stiffness, so a custom casting gets a casting’s density. Custom materials are judged by yield unless you add ductile=0.

To change one property of a library material, name it first.

Flag

-m "pla:yield=40"

Printed parts

Printed plastics are treated as solid, isotropic material at 100% infill, loaded in the plane of the layers. Pulling the layers apart is weaker, from 60% of the in plane strength for PLA, ABS and ASA to 90% for PA12, and --print-direction z tells Wobbl which way the layers stack so that it judges the pull across them against that weaker strength. Without it, the result says how much weaker the part is across its layers and suggests passing the direction.