D40 vs D70

D70 is 1.5 times as stiff as D40. It is 1.5 times as dense. Per unit mass they are about equally stiff (19.7 and 20.83 MJ/kg). Strength: f_m,k = 40 MPa for D40, f_m,k = 70 MPa for D70.

D40 EN 338:2016 D70 EN 338:2016

Side by side

ratio = D70 / D40 · log scale

Property	D40	D70	Unit	Ratio
E₁ Modulus, direction 1	13	20	GPa	1.54×
E₂ Modulus, direction 2	0.87	1.33	GPa	1.53×
E₃ Modulus, direction 3	0.87	1.33	GPa	1.53×
G₁₂ Shear modulus 1-2	0.81	1.25	GPa	1.54×
G₁₃ Shear modulus 1-3	0.81	1.25	GPa	1.54×
E₀,₀₅ Modulus parallel to grain, 5 % fractile	10.9	16.8	GPa	1.54×
ρ Density	660	960	kg/m³	1.45×
ρ_k Density, characteristic (5 % fractile)	550	800	kg/m³	1.45×
f_m,k Bending strength	40	70	MPa	1.75×
f_t,0,k Tension parallel to grain	24	42	MPa	1.75×
f_t,90,k Tension perpendicular to grain	0.6	0.6	MPa	1×
f_c,0,k Compression parallel to grain	27	36	MPa	1.33×
f_c,90,k Compression perpendicular to grain	5.5	12	MPa	2.18×
f_v,k Shear strength	4.2	5	MPa	1.19×
E/ρ Specific stiffness E/ρ · derived	19.7	20.83	MJ/kg	1.06×
c₀ Bar wave speed √(E/ρ) · derived	4438	4564	m/s	1.03×
f/ρ Specific strength f/ρ · derived	60.61	72.92	kJ/kg	1.2×

Values at the first thickness band or product form of each material (EN 338:2016; EN 338:2016). A minimum and a characteristic value are not the same kind of number — read the ratio as a guide. Each material's page lists every band and every source.