Dynamic Foot Model for Impact Investigation - Computational Biomechanics of the Musculoskeletal System - page 67

Load

Gravity

Restrained

FIgure 5.2 Impact boundary condition of the dynamic foot model.

1.6

1.4

1.2

1

0.8

0.6

0.4

0.2

0

0 0 100 150 200 250 300

Time (ms)

350 400 450 500 550 600 650

FIgure 5.3 Vertical ground reaction force during walking.

Markers were placed on the lateral and medial posterior side of the rear foot (Figure 5.4). The data
from GRF measurements and the high-speed camera were synchronized.

5.3.3 r eSultS
The FE model's prediction of a peak GRF of about 60% body weight (BW) within 0.015 sec-
onds was in agreement with experimental data (Figure 5.5). The maximal plantar heel pad com-
pressive deformation was 5.64 mm by experimental measurement and 5.79 mm by FE prediction.
Deformation and compressive strain at heel strike are shown in Figure 5.6.
Chi and Schmitt (2005) reported an impact force during walking at heel strike of 0.79 BW (from
0.37 to 1.41), time to impact peak of 14.61 ms (from 10.33 to 24.00), and compressive deformation
of 5.24 mm (from 2.87 to 8.29). Our experimental and FE predicted data were consistent with these
results. The impact force magnitude is more strongly affected by impact velocity than walking
speed (Whittle 1999; Chi and Schmitt 2005).