PSI - Issue 64

Luca Belluomo et al. / Procedia Structural Integrity 64 (2024) 2197–2205 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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3.2. Bronze Axe The first retrieval considered to be supported is a winged axe (Fig. 3(a)), made in bronze with expanded blade and convex cut with about 140mm of length, height in a range that goes from 30 to 55mm, a width of about 40mm in the handle side, with thickness of the blade that decreases from 14,6mm to 8,6mm from the inner part to the edge. Its weight is about 520g. It is part of the MCAAC goods. It has probably been manufactured through a matrix processing technique with cold finishing. Due to all the common characteristics of this type of retrieval in different periods, an exact chronological classification is still missing, but future analyses will be conducted with this aim. In terms of conservation status, it is almost intact, with the exception of some chipping on the blade and on the attachment. As with many ancient bronze retrievals, the surface is almost oxidized in several areas. The axe has been reverse engineered through photogrammetry, surrounding the object with a virtual cage with 48 points of shooting, obtaining a set of about 150 photograms. The photograms have been processed through Agisoft Metashape, obtaining the virtual model in stl and obj formats. The stl has been processed through CAD software in order to obtain a non-manifold mesh, erasing noise and outliers, and then a set of surfaces, as in Fig. 4(a).

Fig. 4. (a) the 3D model of the axe obtained after RE process; (b) the orientation chosen and optimized in the sagittal plane, in red; (c),(d) the 3D model with the optimized clamps on it.

Through discussions and reasonings with heritage experts, using also Virtual Environments and models, the agreement on the orientation was focused on trying to show to the users the wider portion possible of the object, considering the mentioned positioning for this retrieval, (1) furnished a value of about 36° for ⍺ (Fig. 4(b)). Lately, through the optimization of positions and dimensions of the clamps, the three supporting interfaces have been found and optimized (as in Figg. 4(c), 4(d)).

3.3. Aryballos (Unguentarium)

The second case study is an “Aryballos” (Fig . 3(b)), a little unguentarium, made in clay, with an everted rim, short cylindrical neck, ribbon-like handle, pyriform body and small distinct ring-shaped foot. It is polychrome decorated, with prevalence of black and brown tints and scratched, consisting of a series of scales on the body with alternating white and red dots, darker bullae on the neck and alternating black, brown and sparing bands at the bottom. In terms of conservation status, it is almost intact, with the exception of a small chip on the foot and a gap in the middle of the body; the decoration, although well preserved for the most part, is slightly deteriorated in several places. This retrieval belongs to the group widespread in Etruria and Lazio that imitates the polychrome pyriform Corinthian aryballoi with scales and bacellation decoration of Early Corinthian serial production, this conducted experts to date it around the last quarter of the 7th Century BC. Its weight is about 60g. It is part of the MCAAC goods. Its height is about 90mm, with the superior diameter of the rim in the range 37,9 ÷ 40,7mm. As in the previous case, the aryballos has been reverse engineered through photogrammetry, surrounding the object with a virtual cage with 60 points of shooting, obtaining a set of about 200 photograms. The photograms have been processed through Agisoft Metashape, obtaining the virtual model in stl and obj formats. The stl has been processed through CAD software in order to obtain a non-manifold mesh, erasing noise and outliers, and then a set of surfaces, as in Fig. 5(a). In this case study, the optimal ⍺ resulted to be about 14° (Fig. 5(b)), and the optimized clamps are reported in Figg. 5(c) and 5(d).