Cutting force variability as a consequence of exchangeable cleavage fracture and compressive breakdown of wood tissue

Miran Merhar (Avtor), Bojan Bučar (Avtor)

Povzetek

In the present study, the conditions of chip propagation or fracture in orthogonal oblique cutting of beech wood (Fagus silvatica) in the 90° direction for a type-I chip has been investigated. The force required for orthogonal wood cutting is pronouncedly variable, which is the consequence of exchangeable different ways of material breakdown. The chip formation process is discontinuous because of interrupted splitting of the material in front of the cutting tool. A 10-mm-thick specimen was cut at a rake angle of 31° and 42° with chip thicknesses ranging from 0.1 to 0.3 mm. The chip segment length increased with the chip thickness. A chip of varying length and thickness was modelled using the finite element method. For each case, the bending or compressive stress in the chip and the stress intensity factor at the crack tip was calculated. The segment length of the chip can be calculated by taking into account the condition that a crack propagates when the stress intensity factor K I at the crack tip equals the critical stress intensity factor K IC, and the bending or compressive stress sigma x in the chip is smaller than the strength sigm u . Good agreement between the calculated and the measured values was observed. The chip segment length can change considerably already with small changes in the bending strength and critical stress intensity factor. This large sensitivity is also confirmed by the fluctuation of the measured chip segment lengths by as much as 400%.

Ključne besede

odrezek;segmentacija odrezka;formiranje odrezka;fraktura;

Podatki

Jezik:	Angleški jezik
Leto izida:	2012
Tipologija:	1.01 - Izvirni znanstveni članek
Organizacija:	UL BF - Biotehniška fakulteta
UDK:	630*8
COBISS:	1989001
ISSN:	0043-7719
Št. ogledov:	902
Št. prenosov:	217
Ocena:	0 (0 glasov)
Metapodatki:

Ostali podatki

Sekundarni jezik:	Angleški jezik
Vrsta dela (COBISS):	Delo ni kategorizirano
Strani:	str. 965-977
Letnik:	ǂVol. ǂ46
Zvezek:	ǂissue ǂ5
Čas izdaje:	2012
DOI:	10.1007/s00226-011-0457-4
ID:	1033442