D18 vs D65

D65 is about twice as stiff as D18. It is 1.6 times as dense. Per unit mass D65 is 1.2 times as stiff. Strength: f_m,k = 18 MPa for D18, f_m,k = 65 MPa for D65.

D18 EN 338:2016 D65 EN 338:2016

Side by side

ratio = D65 / D18 · log scale

Property	D18	D65	Unit	Ratio
E₁ Modulus, direction 1	9.5	18.5	GPa	1.95×
E₂ Modulus, direction 2	0.63	1.23	GPa	1.95×
E₃ Modulus, direction 3	0.63	1.23	GPa	1.95×
G₁₂ Shear modulus 1-2	0.59	1.16	GPa	1.97×
G₁₃ Shear modulus 1-3	0.59	1.16	GPa	1.97×
E₀,₀₅ Modulus parallel to grain, 5 % fractile	8	15.5	GPa	1.94×
ρ Density	570	900	kg/m³	1.58×
ρ_k Density, characteristic (5 % fractile)	475	750	kg/m³	1.58×
f_m,k Bending strength	18	65	MPa	3.61×
f_t,0,k Tension parallel to grain	11	39	MPa	3.55×
f_t,90,k Tension perpendicular to grain	0.6	0.6	MPa	1×
f_c,0,k Compression parallel to grain	18	35	MPa	1.94×
f_c,90,k Compression perpendicular to grain	4.8	11.3	MPa	2.35×
f_v,k Shear strength	3.5	5	MPa	1.43×
E/ρ Specific stiffness E/ρ · derived	16.67	20.56	MJ/kg	1.23×
c₀ Bar wave speed √(E/ρ) · derived	4082	4534	m/s	1.11×
f/ρ Specific strength f/ρ · derived	31.58	72.22	kJ/kg	2.29×

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.